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2023-12-11arch: remove ARCH_TASK_STRUCT_ON_STACKHeiko Carstens1-7/+0
IA-64 was the only architecture which selected ARCH_TASK_STRUCT_ON_STACK. IA-64 was removed with commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture"). Therefore remove support for ARCH_TASK_STRUCT_ON_STACK as well. Note: this also reveals a potential bug in powerpc code, which makes use of __init_task_data without selecting ARCH_TASK_STRUCT_ON_STACK which makes __init_task_data a no-op. This is broken since commit d11ed3ab3166 ("Expand INIT_TASK() in init/init_task.c and remove") from 2018 and needs to be addressed separately. Link: https://lkml.kernel.org/r/20231116133638.1636277-4-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2021-05-07kernel/cred.c: make init_groups staticRasmus Villemoes1-1/+0
init_groups is declared in both cred.h and init_task.h, but it is not actually referenced anywhere outside of cred.c where it is defined. So make it static and remove the declarations. Link: https://lkml.kernel.org/r/20210310220102.2484201-1-linux@rasmusvillemoes.dk Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-26treewide: Convert macro and uses of __section(foo) to __section("foo")Joe Perches1-2/+2
Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Nick Desaulniers <ndesaulniers@gooogle.com> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-08-28posix-cpu-timers: Create a container structThomas Gleixner1-11/+0
Per task/process data of posix CPU timers is all over the place which makes the code hard to follow and requires ifdeffery. Create a container to hold all this information in one place, so data is consolidated and the ifdeffery can be confined to the posix timer header file and removed from places like fork. As a first step, move the cpu_timers list head array into the new struct and clean up the initializers and simplify fork. The remaining #ifdef in fork will be removed later. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192920.819418976@linutronix.de
2019-02-04sched/core: Convert task_struct.stack_refcount to refcount_tElena Reshetova1-0/+1
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable task_struct.stack_refcount is used as pure reference counter. Convert it to refcount_t and fix up the operations. ** Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the task_struct.stack_refcount it might make a difference in following places: - try_get_task_stack(): increment in refcount_inc_not_zero() only guarantees control dependency on success vs. fully ordered atomic counterpart - put_task_stack(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1547814450-18902-6-git-send-email-elena.reshetova@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-21pids: Move the pgrp and session pid pointers from task_struct to signal_structEric W. Biederman1-9/+0
To access these fields the code always has to go to group leader so going to signal struct is no loss and is actually a fundamental simplification. This saves a little bit of memory by only allocating the pid pointer array once instead of once for every thread, and even better this removes a few potential races caused by the fact that group_leader can be changed by de_thread, while signal_struct can not. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-01-17Expand INIT_STRUCT_PID and removeDavid Howells1-15/+0
Expand INIT_STRUCT_PID in the single place that uses it and then remove it. There doesn't seem any point in the macro. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-17Expand the INIT_SIGNALS and INIT_SIGHAND macros and removeDavid Howells1-39/+4
There doesn't seem to be any need to have the INIT_SIGNALS and INIT_SIGHAND macros, so expand them in their single places of use and remove them. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-17Expand various INIT_* macros and removeDavid Howells1-112/+0
Expand various INIT_* macros into the single places they're used in init/init_task.c and remove them. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-17Expand INIT_TASK() in init/init_task.c and removeDavid Howells1-83/+4
It's no longer necessary to have an INIT_TASK() macro, and this can be expanded into the one place it is now used and removed. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2018-01-10Construct init thread stack in the linker script rather than by unionDavid Howells1-0/+3
Construct the init thread stack in the linker script rather than doing it by means of a union so that ia64's init_task.c can be got rid of. The following symbols are then made available from INIT_TASK_DATA() linker script macro: init_thread_union init_stack INIT_TASK_DATA() also expands the region to THREAD_SIZE to accommodate the size of the init stack. init_thread_union is given its own section so that it can be placed into the stack space in the right order. I'm assuming that the ia64 ordering is correct and that the task_struct is first and the thread_info second. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Tested-by: Will Deacon <will.deacon@arm.com> (arm64) Tested-by: Palmer Dabbelt <palmer@sifive.com> Acked-by: Thomas Gleixner <tglx@linutronix.de>
2017-11-18pid: remove pidhashGargi Sharma1-1/+0
pidhash is no longer required as all the information can be looked up from idr tree. nr_hashed represented the number of pids that had been hashed. Since, nr_hashed and PIDNS_HASH_ADDING are no longer relevant, it has been renamed to pid_allocated and PIDNS_ADDING respectively. [gs051095@gmail.com: v6] Link: http://lkml.kernel.org/r/1507760379-21662-3-git-send-email-gs051095@gmail.com Link: http://lkml.kernel.org/r/1507583624-22146-3-git-send-email-gs051095@gmail.com Signed-off-by: Gargi Sharma <gs051095@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> [ia64] Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Ingo Molnar <mingo@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-09locking/rtmutex: replace top-waiter and pi_waiters leftmost cachingDavidlohr Bueso1-3/+2
... with the generic rbtree flavor instead. No changes in semantics whatsoever. Link: http://lkml.kernel.org/r/20170719014603.19029-10-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-25init_task: Remove redundant INIT_TASK_RCU_TREE_PREEMPT() macroPaul E. McKenney1-7/+1
Back in the dim distant past, the task_struct structure's RCU-related fields optionally included those needed for CONFIG_RCU_BOOST, even in CONFIG_PREEMPT_RCU builds. The INIT_TASK_RCU_TREE_PREEMPT() macro was used to provide initializers for those optional CONFIG_RCU_BOOST fields. However, the CONFIG_RCU_BOOST fields are now included unconditionally in CONFIG_PREEMPT_RCU builds, so there is no longer any need fro the INIT_TASK_RCU_TREE_PREEMPT() macro. This commit therefore removes it in favor of initializing the ->rcu_blocked_node field directly in the INIT_TASK_RCU_PREEMPT() macro. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-07-05sched/cputime: Move the vtime task fields to their own structFrederic Weisbecker1-3/+3
We are about to add vtime accumulation fields to the task struct. Let's avoid more bloatification and gather vtime information to their own struct. Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05sched/cputime: Rename vtime fieldsFrederic Weisbecker1-2/+2
The current "snapshot" based naming on vtime fields suggests we record some past event but that's a low level picture of their actual purpose which comes out blurry. The real point of these fields is to run a basic state machine that tracks down cputime entry while switching between contexts. So lets reflect that with more meaningful names. Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-03Merge branch 'next' of ↵Linus Torvalds1-0/+7
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security Pull security subsystem updates from James Morris: "Highlights: IMA: - provide ">" and "<" operators for fowner/uid/euid rules KEYS: - add a system blacklist keyring - add KEYCTL_RESTRICT_KEYRING, exposes keyring link restriction functionality to userland via keyctl() LSM: - harden LSM API with __ro_after_init - add prlmit security hook, implement for SELinux - revive security_task_alloc hook TPM: - implement contextual TPM command 'spaces'" * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (98 commits) tpm: Fix reference count to main device tpm_tis: convert to using locality callbacks tpm: fix handling of the TPM 2.0 event logs tpm_crb: remove a cruft constant keys: select CONFIG_CRYPTO when selecting DH / KDF apparmor: Make path_max parameter readonly apparmor: fix parameters so that the permission test is bypassed at boot apparmor: fix invalid reference to index variable of iterator line 836 apparmor: use SHASH_DESC_ON_STACK security/apparmor/lsm.c: set debug messages apparmor: fix boolreturn.cocci warnings Smack: Use GFP_KERNEL for smk_netlbl_mls(). smack: fix double free in smack_parse_opts_str() KEYS: add SP800-56A KDF support for DH KEYS: Keyring asymmetric key restrict method with chaining KEYS: Restrict asymmetric key linkage using a specific keychain KEYS: Add a lookup_restriction function for the asymmetric key type KEYS: Add KEYCTL_RESTRICT_KEYRING KEYS: Consistent ordering for __key_link_begin and restrict check KEYS: Add an optional lookup_restriction hook to key_type ...
2017-05-03Merge branch 'for-linus' of ↵Linus Torvalds1-0/+9
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching Pull livepatch updates from Jiri Kosina: - a per-task consistency model is being added for architectures that support reliable stack dumping (extending this, currently rather trivial set, is currently in the works). This extends the nature of the types of patches that can be applied by live patching infrastructure. The code stems from the design proposal made [1] back in November 2014. It's a hybrid of SUSE's kGraft and RH's kpatch, combining advantages of both: it uses kGraft's per-task consistency and syscall barrier switching combined with kpatch's stack trace switching. There are also a number of fallback options which make it quite flexible. Most of the heavy lifting done by Josh Poimboeuf with help from Miroslav Benes and Petr Mladek [1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz - module load time patch optimization from Zhou Chengming - a few assorted small fixes * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching: livepatch: add missing printk newlines livepatch: Cancel transition a safe way for immediate patches livepatch: Reduce the time of finding module symbols livepatch: make klp_mutex proper part of API livepatch: allow removal of a disabled patch livepatch: add /proc/<pid>/patch_state livepatch: change to a per-task consistency model livepatch: store function sizes livepatch: use kstrtobool() in enabled_store() livepatch: move patching functions into patch.c livepatch: remove unnecessary object loaded check livepatch: separate enabled and patched states livepatch/s390: add TIF_PATCH_PENDING thread flag livepatch/s390: reorganize TIF thread flag bits livepatch/powerpc: add TIF_PATCH_PENDING thread flag livepatch/x86: add TIF_PATCH_PENDING thread flag livepatch: create temporary klp_update_patch_state() stub x86/entry: define _TIF_ALLWORK_MASK flags explicitly stacktrace/x86: add function for detecting reliable stack traces
2017-04-04sched/rtmutex/deadline: Fix a PI crash for deadline tasksXunlei Pang1-0/+1
A crash happened while I was playing with deadline PI rtmutex. BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 IP: [<ffffffff810eeb8f>] rt_mutex_get_top_task+0x1f/0x30 PGD 232a75067 PUD 230947067 PMD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 10994 Comm: a.out Not tainted Call Trace: [<ffffffff810b658c>] enqueue_task+0x2c/0x80 [<ffffffff810ba763>] activate_task+0x23/0x30 [<ffffffff810d0ab5>] pull_dl_task+0x1d5/0x260 [<ffffffff810d0be6>] pre_schedule_dl+0x16/0x20 [<ffffffff8164e783>] __schedule+0xd3/0x900 [<ffffffff8164efd9>] schedule+0x29/0x70 [<ffffffff8165035b>] __rt_mutex_slowlock+0x4b/0xc0 [<ffffffff81650501>] rt_mutex_slowlock+0xd1/0x190 [<ffffffff810eeb33>] rt_mutex_timed_lock+0x53/0x60 [<ffffffff810ecbfc>] futex_lock_pi.isra.18+0x28c/0x390 [<ffffffff810ed8b0>] do_futex+0x190/0x5b0 [<ffffffff810edd50>] SyS_futex+0x80/0x180 This is because rt_mutex_enqueue_pi() and rt_mutex_dequeue_pi() are only protected by pi_lock when operating pi waiters, while rt_mutex_get_top_task(), will access them with rq lock held but not holding pi_lock. In order to tackle it, we introduce new "pi_top_task" pointer cached in task_struct, and add new rt_mutex_update_top_task() to update its value, it can be called by rt_mutex_setprio() which held both owner's pi_lock and rq lock. Thus "pi_top_task" can be safely accessed by enqueue_task_dl() under rq lock. Originally-From: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Xunlei Pang <xlpang@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170323150216.157682758@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-03-28LSM: Revive security_task_alloc() hook and per "struct task_struct" security ↵Tetsuo Handa1-0/+7
blob. We switched from "struct task_struct"->security to "struct cred"->security in Linux 2.6.29. But not all LSM modules were happy with that change. TOMOYO LSM module is an example which want to use per "struct task_struct" security blob, for TOMOYO's security context is defined based on "struct task_struct" rather than "struct cred". AppArmor LSM module is another example which want to use it, for AppArmor is currently abusing the cred a little bit to store the change_hat and setexeccon info. Although security_task_free() hook was revived in Linux 3.4 because Yama LSM module wanted to release per "struct task_struct" security blob, security_task_alloc() hook and "struct task_struct"->security field were not revived. Nowadays, we are getting proposals of lightweight LSM modules which want to use per "struct task_struct" security blob. We are already allowing multiple concurrent LSM modules (up to one fully armored module which uses "struct cred"->security field or exclusive hooks like security_xfrm_state_pol_flow_match(), plus unlimited number of lightweight modules which do not use "struct cred"->security nor exclusive hooks) as long as they are built into the kernel. But this patch does not implement variable length "struct task_struct"->security field which will become needed when multiple LSM modules want to use "struct task_struct"-> security field. Although it won't be difficult to implement variable length "struct task_struct"->security field, let's think about it after we merged this patch. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Serge Hallyn <serge@hallyn.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Tested-by: Djalal Harouni <tixxdz@gmail.com> Acked-by: José Bollo <jobol@nonadev.net> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Eric Paris <eparis@parisplace.org> Cc: Kees Cook <keescook@chromium.org> Cc: James Morris <james.l.morris@oracle.com> Cc: José Bollo <jobol@nonadev.net> Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-03-08livepatch: change to a per-task consistency modelJosh Poimboeuf1-0/+9
Change livepatch to use a basic per-task consistency model. This is the foundation which will eventually enable us to patch those ~10% of security patches which change function or data semantics. This is the biggest remaining piece needed to make livepatch more generally useful. This code stems from the design proposal made by Vojtech [1] in November 2014. It's a hybrid of kGraft and kpatch: it uses kGraft's per-task consistency and syscall barrier switching combined with kpatch's stack trace switching. There are also a number of fallback options which make it quite flexible. Patches are applied on a per-task basis, when the task is deemed safe to switch over. When a patch is enabled, livepatch enters into a transition state where tasks are converging to the patched state. Usually this transition state can complete in a few seconds. The same sequence occurs when a patch is disabled, except the tasks converge from the patched state to the unpatched state. An interrupt handler inherits the patched state of the task it interrupts. The same is true for forked tasks: the child inherits the patched state of the parent. Livepatch uses several complementary approaches to determine when it's safe to patch tasks: 1. The first and most effective approach is stack checking of sleeping tasks. If no affected functions are on the stack of a given task, the task is patched. In most cases this will patch most or all of the tasks on the first try. Otherwise it'll keep trying periodically. This option is only available if the architecture has reliable stacks (HAVE_RELIABLE_STACKTRACE). 2. The second approach, if needed, is kernel exit switching. A task is switched when it returns to user space from a system call, a user space IRQ, or a signal. It's useful in the following cases: a) Patching I/O-bound user tasks which are sleeping on an affected function. In this case you have to send SIGSTOP and SIGCONT to force it to exit the kernel and be patched. b) Patching CPU-bound user tasks. If the task is highly CPU-bound then it will get patched the next time it gets interrupted by an IRQ. c) In the future it could be useful for applying patches for architectures which don't yet have HAVE_RELIABLE_STACKTRACE. In this case you would have to signal most of the tasks on the system. However this isn't supported yet because there's currently no way to patch kthreads without HAVE_RELIABLE_STACKTRACE. 3. For idle "swapper" tasks, since they don't ever exit the kernel, they instead have a klp_update_patch_state() call in the idle loop which allows them to be patched before the CPU enters the idle state. (Note there's not yet such an approach for kthreads.) All the above approaches may be skipped by setting the 'immediate' flag in the 'klp_patch' struct, which will disable per-task consistency and patch all tasks immediately. This can be useful if the patch doesn't change any function or data semantics. Note that, even with this flag set, it's possible that some tasks may still be running with an old version of the function, until that function returns. There's also an 'immediate' flag in the 'klp_func' struct which allows you to specify that certain functions in the patch can be applied without per-task consistency. This might be useful if you want to patch a common function like schedule(), and the function change doesn't need consistency but the rest of the patch does. For architectures which don't have HAVE_RELIABLE_STACKTRACE, the user must set patch->immediate which causes all tasks to be patched immediately. This option should be used with care, only when the patch doesn't change any function or data semantics. In the future, architectures which don't have HAVE_RELIABLE_STACKTRACE may be allowed to use per-task consistency if we can come up with another way to patch kthreads. The /sys/kernel/livepatch/<patch>/transition file shows whether a patch is in transition. Only a single patch (the topmost patch on the stack) can be in transition at a given time. A patch can remain in transition indefinitely, if any of the tasks are stuck in the initial patch state. A transition can be reversed and effectively canceled by writing the opposite value to the /sys/kernel/livepatch/<patch>/enabled file while the transition is in progress. Then all the tasks will attempt to converge back to the original patch state. [1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Ingo Molnar <mingo@kernel.org> # for the scheduler changes Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-03-03sched/headers: Move the 'root_task_group' declaration to ↵Ingo Molnar1-2/+0
<linux/sched/autogroup.h> Also remove the duplicate declaration from <linux/init_task.h>. ( That declaration was originally duplicated for dependency hell reasons, but there's no problem including the much smaller <linux/sched/autogroup.h> header now, to pick up the right prototype. ) Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare to remove the <linux/mm_types.h> dependency from ↵Ingo Molnar1-0/+1
<linux/sched.h> Update code that relied on sched.h including various MM types for them. This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02sched/headers: Prepare to move the 'root_task_group' declaration to ↵Ingo Molnar1-0/+1
<linux/sched/autogroup.h> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-28timers: Omit POSIX timer stuff from task_struct when disabledNicolas Pitre1-15/+25
When CONFIG_POSIX_TIMERS is disabled, it is preferable to remove related structures from struct task_struct and struct signal_struct as they won't contain anything useful and shouldn't be relied upon by mistake. Code still referencing those structures is also disabled here. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-09-16sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASKAndy Lutomirski1-1/+3
We currently keep every task's stack around until the task_struct itself is freed. This means that we keep the stack allocation alive for longer than necessary and that, under load, we free stacks in big batches whenever RCU drops the last task reference. Neither of these is good for reuse of cache-hot memory, and freeing in batches prevents us from usefully caching small numbers of vmalloced stacks. On architectures that have thread_info on the stack, we can't easily change this, but on architectures that set THREAD_INFO_IN_TASK, we can free it as soon as the task is dead. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/08ca06cde00ebed0046c5d26cbbf3fbb7ef5b812.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-09-15sched/core: Allow putting thread_info into task_structAndy Lutomirski1-0/+9
If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jann Horn <jann@thejh.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-25fix up initial thread stack pointer vs thread_info confusionLinus Torvalds1-1/+1
The INIT_TASK() initializer was similarly confused about the stack vs thread_info allocation that the allocators had, and that were fixed in commit b235beea9e99 ("Clarify naming of thread info/stack allocators"). The task ->stack pointer only incidentally ends up having the same value as the thread_info, and in fact that will change. So fix the initial task struct initializer to point to 'init_stack' instead of 'init_thread_info', and make sure the ia64 definition for that exists. This actually makes the ia64 tsk->stack pointer be sensible for the initial task, but not for any other task. As mentioned in commit b235beea9e99, that whole pointer isn't actually used on ia64, since task_stack_page() there just points to the (single) allocation. All the other architectures seem to have copied the 'init_stack' definition, even if it tended to be generally unusued. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-12-04sched/cputime: Convert vtime_seqlock to seqcountFrederic Weisbecker1-1/+1
The cputime can only be updated by the current task itself, even in vtime case. So we can safely use seqcount instead of seqlock as there is no writer concurrency involved. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1447948054-28668-8-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-06Merge branch 'for-4.4' of ↵Linus Torvalds1-8/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "The cgroup core saw several significant updates this cycle: - percpu_rwsem for threadgroup locking is reinstated. This was temporarily dropped due to down_write latency issues. Oleg's rework of percpu_rwsem which is scheduled to be merged in this merge window resolves the issue. - On the v2 hierarchy, when controllers are enabled and disabled, all operations are atomic and can fail and revert cleanly. This allows ->can_attach() failure which is necessary for cpu RT slices. - Tasks now stay associated with the original cgroups after exit until released. This allows tracking resources held by zombies (e.g. pids) and makes it easy to find out where zombies came from on the v2 hierarchy. The pids controller was broken before these changes as zombies escaped the limits; unfortunately, updating this behavior required too many invasive changes and I don't think it's a good idea to backport them, so the pids controller on 4.3, the first version which included the pids controller, will stay broken at least until I'm sure about the cgroup core changes. - Optimization of a couple common tests using static_key" * 'for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (38 commits) cgroup: fix race condition around termination check in css_task_iter_next() blkcg: don't create "io.stat" on the root cgroup cgroup: drop cgroup__DEVEL__legacy_files_on_dfl cgroup: replace error handling in cgroup_init() with WARN_ON()s cgroup: add cgroup_subsys->free() method and use it to fix pids controller cgroup: keep zombies associated with their original cgroups cgroup: make css_set_rwsem a spinlock and rename it to css_set_lock cgroup: don't hold css_set_rwsem across css task iteration cgroup: reorganize css_task_iter functions cgroup: factor out css_set_move_task() cgroup: keep css_set and task lists in chronological order cgroup: make cgroup_destroy_locked() test cgroup_is_populated() cgroup: make css_sets pin the associated cgroups cgroup: relocate cgroup_[try]get/put() cgroup: move check_for_release() invocation cgroup: replace cgroup_has_tasks() with cgroup_is_populated() cgroup: make cgroup->nr_populated count the number of populated css_sets cgroup: remove an unused parameter from cgroup_task_migrate() cgroup: fix too early usage of static_branch_disable() cgroup: make cgroup_update_dfl_csses() migrate all target processes atomically ...
2015-10-15posix_cpu_timer: Reduce unnecessary sighand lock contentionJason Low1-0/+1
It was found while running a database workload on large systems that significant time was spent trying to acquire the sighand lock. The issue was that whenever an itimer expired, many threads ended up simultaneously trying to send the signal. Most of the time, nothing happened after acquiring the sighand lock because another thread had just already sent the signal and updated the "next expire" time. The fastpath_timer_check() didn't help much since the "next expire" time was updated after the threads exit fastpath_timer_check(). This patch addresses this by having the thread_group_cputimer structure maintain a boolean to signify when a thread in the group is already checking for process wide timers, and adds extra logic in the fastpath to check the boolean. Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: George Spelvin <linux@horizon.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-5-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-10-15posix_cpu_timer: Convert cputimer->running to boolJason Low1-1/+1
In the next patch in this series, a new field 'checking_timer' will be added to 'struct thread_group_cputimer'. Both this and the existing 'running' integer field are just used as boolean values. To save space in the structure, we can make both of these fields booleans. This is a preparatory patch to convert the existing running integer field to a boolean. Suggested-by: George Spelvin <linux@horizon.com> Signed-off-by: Jason Low <jason.low2@hp.com> Reviewed: George Spelvin <linux@horizon.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: hideaki.kimura@hpe.com Cc: terry.rudd@hpe.com Cc: scott.norton@hpe.com Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1444849677-29330-4-git-send-email-jason.low2@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-16sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsemTejun Heo1-8/+0
Note: This commit was originally committed as d59cfc09c32a but got reverted by 0c986253b939 due to the performance regression from the percpu_rwsem write down/up operations added to cgroup task migration path. percpu_rwsem changes which alleviate the performance issue are pending for v4.4-rc1 merge window. Re-apply. The cgroup side of threadgroup locking uses signal_struct->group_rwsem to synchronize against threadgroup changes. This per-process rwsem adds small overhead to thread creation, exit and exec paths, forces cgroup code paths to do lock-verify-unlock-retry dance in a couple places and makes it impossible to atomically perform operations across multiple processes. This patch replaces signal_struct->group_rwsem with a global percpu_rwsem cgroup_threadgroup_rwsem which is cheaper on the reader side and contained in cgroups proper. This patch converts one-to-one. This does make writer side heavier and lower the granularity; however, cgroup process migration is a fairly cold path, we do want to optimize thread operations over it and cgroup migration operations don't take enough time for the lower granularity to matter. Signed-off-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2015-09-16Revert "sched, cgroup: replace signal_struct->group_rwsem with a global ↵Tejun Heo1-0/+8
percpu_rwsem" This reverts commit d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14. d59cfc09c32a ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem") and b5ba75b5fc0e ("cgroup: simplify threadgroup locking") changed how cgroup synchronizes against task fork and exits so that it uses global percpu_rwsem instead of per-process rwsem; unfortunately, the write [un]lock paths of percpu_rwsem always involve synchronize_rcu_expedited() which turned out to be too expensive. Improvements for percpu_rwsem are scheduled to be merged in the coming v4.4-rc1 merge window which alleviates this issue. For now, revert the two commits to restore per-process rwsem. They will be re-applied for the v4.4-rc1 merge window. Signed-off-by: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: stable@vger.kernel.org # v4.2+
2015-08-03sched/cputime: Guarantee stime + utime == rtimePeter Zijlstra1-0/+10
While the current code guarantees monotonicity for stime and utime independently of one another, it does not guarantee that the sum of both is equal to the total time we started out with. This confuses things (and peoples) who look at this sum, like top, and will report >100% usage followed by a matching period of 0%. Rework the code to provide both individual monotonicity and a coherent sum. Suggested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Reported-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Tested-by: Fredrik Markstrom <fredrik.markstrom@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jason.low2@hp.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-27Merge branch 'for-4.2' of ↵Linus Torvalds1-8/+0
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - threadgroup_lock got reorganized so that its users can pick the actual locking mechanism to use. Its only user - cgroups - is updated to use a percpu_rwsem instead of per-process rwsem. This makes things a bit lighter on hot paths and allows cgroups to perform and fail multi-task (a process) migrations atomically. Multi-task migrations are used in several places including the unified hierarchy. - Delegation rule and documentation added to unified hierarchy. This will likely be the last interface update from the cgroup core side for unified hierarchy before lifting the devel mask. - Some groundwork for the pids controller which is scheduled to be merged in the coming devel cycle. * 'for-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: add delegation section to unified hierarchy documentation cgroup: require write perm on common ancestor when moving processes on the default hierarchy cgroup: separate out cgroup_procs_write_permission() from __cgroup_procs_write() kernfs: make kernfs_get_inode() public MAINTAINERS: add a cgroup core co-maintainer cgroup: fix uninitialised iterator in for_each_subsys_which cgroup: replace explicit ss_mask checking with for_each_subsys_which cgroup: use bitmask to filter for_each_subsys cgroup: add seq_file forward declaration for struct cftype cgroup: simplify threadgroup locking sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem sched, cgroup: reorganize threadgroup locking cgroup: switch to unsigned long for bitmasks cgroup: reorganize include/linux/cgroup.h cgroup: separate out include/linux/cgroup-defs.h cgroup: fix some comment typos
2015-05-27sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsemTejun Heo1-8/+0
The cgroup side of threadgroup locking uses signal_struct->group_rwsem to synchronize against threadgroup changes. This per-process rwsem adds small overhead to thread creation, exit and exec paths, forces cgroup code paths to do lock-verify-unlock-retry dance in a couple places and makes it impossible to atomically perform operations across multiple processes. This patch replaces signal_struct->group_rwsem with a global percpu_rwsem cgroup_threadgroup_rwsem which is cheaper on the reader side and contained in cgroups proper. This patch converts one-to-one. This does make writer side heavier and lower the granularity; however, cgroup process migration is a fairly cold path, we do want to optimize thread operations over it and cgroup migration operations don't take enough time for the lower granularity to matter. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2015-05-08sched, timer: Use the atomic task_cputime in thread_group_cputimerJason Low1-4/+2
Recent optimizations were made to thread_group_cputimer to improve its scalability by keeping track of cputime stats without a lock. However, the values were open coded to the structure, causing them to be at a different abstraction level from the regular task_cputime structure. Furthermore, any subsequent similar optimizations would not be able to share the new code, since they are specific to thread_group_cputimer. This patch adds the new task_cputime_atomic data structure (introduced in the previous patch in the series) to thread_group_cputimer for keeping track of the cputime atomically, which also helps generalize the code. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Jason Low <jason.low2@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1430251224-5764-6-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-08sched, timer: Replace spinlocks with atomics in thread_group_cputimer(), to ↵Jason Low1-3/+4
improve scalability While running a database workload, we found a scalability issue with itimers. Much of the problem was caused by the thread_group_cputimer spinlock. Each time we account for group system/user time, we need to obtain a thread_group_cputimer's spinlock to update the timers. On larger systems (such as a 16 socket machine), this caused more than 30% of total time spent trying to obtain this kernel lock to update these group timer stats. This patch converts the timers to 64-bit atomic variables and use atomic add to update them without a lock. With this patch, the percent of total time spent updating thread group cputimer timers was reduced from 30% down to less than 1%. Note: On 32-bit systems using the generic 64-bit atomics, this causes sample_group_cputimer() to take locks 3 times instead of just 1 time. However, we tested this patch on a 32-bit system ARM system using the generic atomics and did not find the overhead to be much of an issue. An explanation for why this isn't an issue is that 32-bit systems usually have small numbers of CPUs, and cacheline contention from extra spinlocks called periodically is not really apparent on smaller systems. Signed-off-by: Jason Low <jason.low2@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Waiman Long <Waiman.Long@hp.com> Link: http://lkml.kernel.org/r/1430251224-5764-4-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-14kasan: enable stack instrumentationAndrey Ryabinin1-0/+8
Stack instrumentation allows to detect out of bounds memory accesses for variables allocated on stack. Compiler adds redzones around every variable on stack and poisons redzones in function's prologue. Such approach significantly increases stack usage, so all in-kernel stacks size were doubled. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13all arches, signal: move restart_block to struct task_structAndy Lutomirski1-0/+3
If an attacker can cause a controlled kernel stack overflow, overwriting the restart block is a very juicy exploit target. This is because the restart_block is held in the same memory allocation as the kernel stack. Moving the restart block to struct task_struct prevents this exploit by making the restart_block harder to locate. Note that there are other fields in thread_info that are also easy targets, at least on some architectures. It's also a decent simplification, since the restart code is more or less identical on all architectures. [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: David Miller <davem@davemloft.net> Acked-by: Richard Weinberger <richard@nod.at> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Steven Miao <realmz6@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-10Merge branch 'sched-core-for-linus' of ↵Linus Torvalds1-0/+10
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes in this cycle are: - 'Nested Sleep Debugging', activated when CONFIG_DEBUG_ATOMIC_SLEEP=y. This instruments might_sleep() checks to catch places that nest blocking primitives - such as mutex usage in a wait loop. Such bugs can result in hard to debug races/hangs. Another category of invalid nesting that this facility will detect is the calling of blocking functions from within schedule() -> sched_submit_work() -> blk_schedule_flush_plug(). There's some potential for false positives (if secondary blocking primitives themselves are not ready yet for this facility), but the kernel will warn once about such bugs per bootup, so the warning isn't much of a nuisance. This feature comes with a number of fixes, for problems uncovered with it, so no messages are expected normally. - Another round of sched/numa optimizations and refinements, for CONFIG_NUMA_BALANCING=y. - Another round of sched/dl fixes and refinements. Plus various smaller fixes and cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits) sched: Add missing rcu protection to wake_up_all_idle_cpus sched/deadline: Introduce start_hrtick_dl() for !CONFIG_SCHED_HRTICK sched/numa: Init numa balancing fields of init_task sched/deadline: Remove unnecessary definitions in cpudeadline.h sched/cpupri: Remove unnecessary definitions in cpupri.h sched/deadline: Fix rq->dl.pushable_tasks bug in push_dl_task() sched/fair: Fix stale overloaded status in the busiest group finding logic sched: Move p->nr_cpus_allowed check to select_task_rq() sched/completion: Document when to use wait_for_completion_io_*() sched: Update comments about CLONE_NEWUTS and CLONE_NEWIPC sched/fair: Kill task_struct::numa_entry and numa_group::task_list sched: Refactor task_struct to use numa_faults instead of numa_* pointers sched/deadline: Don't check CONFIG_SMP in switched_from_dl() sched/deadline: Reschedule from switched_from_dl() after a successful pull sched/deadline: Push task away if the deadline is equal to curr during wakeup sched/deadline: Add deadline rq status print sched/deadline: Fix artificial overrun introduced by yield_task_dl() sched/rt: Clean up check_preempt_equal_prio() sched/core: Use dl_bw_of() under rcu_read_lock_sched() sched: Check if we got a shallowest_idle_cpu before searching for least_loaded_cpu ...
2014-11-16sched/numa: Init numa balancing fields of init_taskKirill Tkhai1-0/+10
We do not initialize init_task.numa_preferred_nid, but this value is inherited by userspace "init" process: rest_init()->kernel_thread(kernel_init)->do_fork(CLONE_VM); __sched_fork() { if (clone_flags & CLONE_VM) p->numa_preferred_nid = current->numa_preferred_nid; else p->numa_preferred_nid = -1; } kernel_init() becomes userspace "init" process. So, we propagate garbage nid to userspace, and it may be used during numa balancing. Currently, we do not have reports about this brings a problem, but it seem we should set it for sure. Even if init_task.numa_preferred_nid is zero, we may meet a weird configuration without nid#0. On sparc64, where processors are numbered physically, I saw a machine without cpu#1, while cpu#2 existed. Possible, something similar may be with numa nodes. So, let's initialize it and be sure we're safe. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Eric Paris <eparis@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Sergey Dyasly <dserrg@gmail.com> Link: http://lkml.kernel.org/r/1415699189.15631.6.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-29rcu: Remove redundant TREE_PREEMPT_RCU config optionPranith Kumar1-1/+1
PREEMPT_RCU and TREE_PREEMPT_RCU serve the same function after TINY_PREEMPT_RCU has been removed. This patch removes TREE_PREEMPT_RCU and uses PREEMPT_RCU config option in its place. Signed-off-by: Pranith Kumar <bobby.prani@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-08rcu: Remove local_irq_disable() in rcu_preempt_note_context_switch()Paul E. McKenney1-1/+1
The rcu_preempt_note_context_switch() function is on a scheduling fast path, so it would be good to avoid disabling irqs. The reason that irqs are disabled is to synchronize process-level and irq-handler access to the task_struct ->rcu_read_unlock_special bitmask. This commit therefore makes ->rcu_read_unlock_special instead be a union of bools with a short allowing single-access checks in RCU's __rcu_read_unlock(). This results in the process-level and irq-handler accesses being simple loads and stores, so that irqs need no longer be disabled. This commit therefore removes the irq disabling from rcu_preempt_note_context_switch(). Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-08rcu: Make TASKS_RCU handle nohz_full= CPUsPaul E. McKenney1-1/+2
Currently TASKS_RCU would ignore a CPU running a task in nohz_full= usermode execution. There would be neither a context switch nor a scheduling-clock interrupt to tell TASKS_RCU that the task in question had passed through a quiescent state. The grace period would therefore extend indefinitely. This commit therefore makes RCU's dyntick-idle subsystem record the task_struct structure of the task that is running in dyntick-idle mode on each CPU. The TASKS_RCU grace period can then access this information and record a quiescent state on behalf of any CPU running in dyntick-idle usermode. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-08rcu: Add call_rcu_tasks()Paul E. McKenney1-0/+9
This commit adds a new RCU-tasks flavor of RCU, which provides call_rcu_tasks(). This RCU flavor's quiescent states are voluntary context switch (not preemption!) and userspace execution (not the idle loop -- use some sort of schedule_on_each_cpu() if you need to handle the idle tasks. Note that unlike other RCU flavors, these quiescent states occur in tasks, not necessarily CPUs. Includes fixes from Steven Rostedt. This RCU flavor is assumed to have very infrequent latency-tolerant updaters. This assumption permits significant simplifications, including a single global callback list protected by a single global lock, along with a single task-private linked list containing all tasks that have not yet passed through a quiescent state. If experience shows this assumption to be incorrect, the required additional complexity will be added. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-07-09rcu: Simplify priority boosting by putting rt_mutex in rcu_nodePaul E. McKenney1-8/+1
RCU priority boosting currently checks for boosting via a pointer in task_struct. However, this is not needed: As Oleg noted, if the rt_mutex is placed in the rcu_node instead of on the booster's stack, the boostee can simply check it see if it owns the lock. This commit makes this change, shrinking task_struct by one pointer and the kernel by thirteen lines. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-01-24Merge git://git.infradead.org/users/eparis/auditLinus Torvalds1-1/+1
Pull audit update from Eric Paris: "Again we stayed pretty well contained inside the audit system. Venturing out was fixing a couple of function prototypes which were inconsistent (didn't hurt anything, but we used the same value as an int, uint, u32, and I think even a long in a couple of places). We also made a couple of minor changes to when a couple of LSMs called the audit system. We hoped to add aarch64 audit support this go round, but it wasn't ready. I'm disappearing on vacation on Thursday. I should have internet access, but it'll be spotty. If anything goes wrong please be sure to cc rgb@redhat.com. He'll make fixing things his top priority" * git://git.infradead.org/users/eparis/audit: (50 commits) audit: whitespace fix in kernel-parameters.txt audit: fix location of __net_initdata for audit_net_ops audit: remove pr_info for every network namespace audit: Modify a set of system calls in audit class definitions audit: Convert int limit uses to u32 audit: Use more current logging style audit: Use hex_byte_pack_upper audit: correct a type mismatch in audit_syscall_exit() audit: reorder AUDIT_TTY_SET arguments audit: rework AUDIT_TTY_SET to only grab spin_lock once audit: remove needless switch in AUDIT_SET audit: use define's for audit version audit: documentation of audit= kernel parameter audit: wait_for_auditd rework for readability audit: update MAINTAINERS audit: log task info on feature change audit: fix incorrect set of audit_sock audit: print error message when fail to create audit socket audit: fix dangling keywords in audit_log_set_loginuid() output audit: log on errors from filter user rules ...