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authorLinus Torvalds <torvalds@linux-foundation.org>2020-12-15 05:35:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-15 05:35:53 +0300
commitedd7ab76847442e299af64a761febd180d71f98d (patch)
tree91c3ee6ca27074c655bc1aaf04358f4e41df54d4 /lib
parentadb35e8dc98ba9bda99ff79ac6a05b8fcde2a762 (diff)
parent68061c02bb295da4955f0d309b9459f0a7ba83dd (diff)
downloadlinux-edd7ab76847442e299af64a761febd180d71f98d.tar.xz
Merge tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull kmap updates from Thomas Gleixner: "The new preemtible kmap_local() implementation: - Consolidate all kmap_atomic() internals into a generic implementation which builds the base for the kmap_local() API and make the kmap_atomic() interface wrappers which handle the disabling/enabling of preemption and pagefaults. - Switch the storage from per-CPU to per task and provide scheduler support for clearing mapping when scheduling out and restoring them when scheduling back in. - Merge the migrate_disable/enable() code, which is also part of the scheduler pull request. This was required to make the kmap_local() interface available which does not disable preemption when a mapping is established. It has to disable migration instead to guarantee that the virtual address of the mapped slot is the same across preemption. - Provide better debug facilities: guard pages and enforced utilization of the mapping mechanics on 64bit systems when the architecture allows it. - Provide the new kmap_local() API which can now be used to cleanup the kmap_atomic() usage sites all over the place. Most of the usage sites do not require the implicit disabling of preemption and pagefaults so the penalty on 64bit and 32bit non-highmem systems is removed and quite some of the code can be simplified. A wholesale conversion is not possible because some usage depends on the implicit side effects and some need to be cleaned up because they work around these side effects. The migrate disable side effect is only effective on highmem systems and when enforced debugging is enabled. On 64bit and 32bit non-highmem systems the overhead is completely avoided" * tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) ARM: highmem: Fix cache_is_vivt() reference x86/crashdump/32: Simplify copy_oldmem_page() io-mapping: Provide iomap_local variant mm/highmem: Provide kmap_local* sched: highmem: Store local kmaps in task struct x86: Support kmap_local() forced debugging mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL microblaze/mm/highmem: Add dropped #ifdef back xtensa/mm/highmem: Make generic kmap_atomic() work correctly mm/highmem: Take kmap_high_get() properly into account highmem: High implementation details and document API Documentation/io-mapping: Remove outdated blurb io-mapping: Cleanup atomic iomap mm/highmem: Remove the old kmap_atomic cruft highmem: Get rid of kmap_types.h xtensa/mm/highmem: Switch to generic kmap atomic sparc/mm/highmem: Switch to generic kmap atomic powerpc/mm/highmem: Switch to generic kmap atomic nds32/mm/highmem: Switch to generic kmap atomic ...
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug22
1 files changed, 22 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c789b39ed527..e952f892f047 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -849,9 +849,31 @@ config DEBUG_PER_CPU_MAPS
Say N if unsure.
+config DEBUG_KMAP_LOCAL
+ bool "Debug kmap_local temporary mappings"
+ depends on DEBUG_KERNEL && KMAP_LOCAL
+ help
+ This option enables additional error checking for the kmap_local
+ infrastructure. Disable for production use.
+
+config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
+ bool
+
+config DEBUG_KMAP_LOCAL_FORCE_MAP
+ bool "Enforce kmap_local temporary mappings"
+ depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
+ select KMAP_LOCAL
+ select DEBUG_KMAP_LOCAL
+ help
+ This option enforces temporary mappings through the kmap_local
+ mechanism for non-highmem pages and on non-highmem systems.
+ Disable this for production systems!
+
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
+ select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
+ select DEBUG_KMAP_LOCAL
help
This option enables additional error checking for high memory
systems. Disable for production systems.