| Age | Commit message (Collapse) | Author | Files | Lines |
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This cleans up handling MADV_SOFT_OFFLINE and MADV_HWPOISON called
through madvise() system call.
* madvise_memory_failure() was misleading to accommodate handling of
both memory_failure() as well as soft_offline_page() functions.
Basically it handles memory error injection from user space which
can go either way as memory failure or soft offline. Renamed as
madvise_inject_error() instead.
* Renamed struct page pointer 'p' to 'page'.
* pr_info() was essentially printing PFN value but it said 'page'
which was misleading. Made the process virtual address explicit.
Before the patch:
Soft offlining page 0x15e3e at 0x3fff8c230000
Soft offlining page 0x1f3 at 0x3fffa0da0000
Soft offlining page 0x744 at 0x3fff7d200000
Soft offlining page 0x1634d at 0x3fff95e20000
Soft offlining page 0x16349 at 0x3fff95e30000
Soft offlining page 0x1d6 at 0x3fff9e8b0000
Soft offlining page 0x5f3 at 0x3fff91bd0000
Injecting memory failure for page 0x15c8b at 0x3fff83280000
Injecting memory failure for page 0x16190 at 0x3fff83290000
Injecting memory failure for page 0x740 at 0x3fff9a2e0000
Injecting memory failure for page 0x741 at 0x3fff9a2f0000
After the patch:
Soft offlining pfn 0x1484e at process virtual address 0x3fff883c0000
Soft offlining pfn 0x1484f at process virtual address 0x3fff883d0000
Soft offlining pfn 0x14850 at process virtual address 0x3fff883e0000
Soft offlining pfn 0x14851 at process virtual address 0x3fff883f0000
Soft offlining pfn 0x14852 at process virtual address 0x3fff88400000
Soft offlining pfn 0x14853 at process virtual address 0x3fff88410000
Soft offlining pfn 0x14854 at process virtual address 0x3fff88420000
Soft offlining pfn 0x1521c at process virtual address 0x3fff6bc70000
Injecting memory failure for pfn 0x10fcf at process virtual address 0x3fff86310000
Injecting memory failure for pfn 0x10fd0 at process virtual address 0x3fff86320000
Injecting memory failure for pfn 0x10fd1 at process virtual address 0x3fff86330000
Injecting memory failure for pfn 0x10fd2 at process virtual address 0x3fff86340000
Injecting memory failure for pfn 0x10fd3 at process virtual address 0x3fff86350000
Injecting memory failure for pfn 0x10fd4 at process virtual address 0x3fff86360000
Injecting memory failure for pfn 0x10fd5 at process virtual address 0x3fff86370000
Link: http://lkml.kernel.org/r/20170410084701.11248-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Adding a brief overview of hugetlbfs reservation design and
implementation as an aid to those making code modifications in this
area.
Link: http://lkml.kernel.org/r/1491586995-13085-1-git-send-email-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is a code cleanup patch, no functionality changes. There are 2
unused function prototype in swap.h, they are removed.
Link: http://lkml.kernel.org/r/20170405071017.23677-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The memory controllers stat function names are awkwardly long and
arbitrarily different from the zone and node stat functions.
The current interface is named:
mem_cgroup_read_stat()
mem_cgroup_update_stat()
mem_cgroup_inc_stat()
mem_cgroup_dec_stat()
mem_cgroup_update_page_stat()
mem_cgroup_inc_page_stat()
mem_cgroup_dec_page_stat()
This patch renames it to match the corresponding node stat functions:
memcg_page_state() [node_page_state()]
mod_memcg_state() [mod_node_state()]
inc_memcg_state() [inc_node_state()]
dec_memcg_state() [dec_node_state()]
mod_memcg_page_state() [mod_node_page_state()]
inc_memcg_page_state() [inc_node_page_state()]
dec_memcg_page_state() [dec_node_page_state()]
Link: http://lkml.kernel.org/r/20170404220148.28338-4-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The current duplication is a high-maintenance mess, and it's painful to
add new items or query memcg state from the rest of the VM.
This increases the size of the stat array marginally, but we should aim
to track all these stats on a per-cgroup level anyway.
Link: http://lkml.kernel.org/r/20170404220148.28338-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The current duplication is a high-maintenance mess, and it's painful to
add new items.
This increases the size of the event array, but we'll eventually want
most of the VM events tracked on a per-cgroup basis anyway.
Link: http://lkml.kernel.org/r/20170404220148.28338-2-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We only ever count single events, drop the @nr parameter. Rename the
function accordingly. Remove low-information kerneldoc.
Link: http://lkml.kernel.org/r/20170404220148.28338-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since commit 59dc76b0d4df ("mm: vmscan: reduce size of inactive file
list") we noticed bigger IO spikes during changes in cache access
patterns.
The patch in question shrunk the inactive list size to leave more room
for the current workingset in the presence of streaming IO. However,
workingset transitions that previously happened on the inactive list are
now pushed out of memory and incur more refaults to complete.
This patch disables active list protection when refaults are being
observed. This accelerates workingset transitions, and allows more of
the new set to establish itself from memory, without eating into the
ability to protect the established workingset during stable periods.
The workloads that were measurably affected for us were hit pretty bad
by it, with refault/majfault rates doubling and tripling during cache
transitions, and the machines sustaining half-hour periods of 100% IO
utilization, where they'd previously have sub-minute peaks at 60-90%.
Stateful services that handle user data tend to be more conservative
with kernel upgrades. As a result we hit most page cache issues with
some delay, as was the case here.
The severity seemed to warrant a stable tag.
Fixes: 59dc76b0d4df ("mm: vmscan: reduce size of inactive file list")
Link: http://lkml.kernel.org/r/20170404220052.27593-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org> [4.7+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 091d0d55b286 ("shm: fix null pointer deref when userspace
specifies invalid hugepage size") had replaced MAP_HUGE_MASK with
SHM_HUGE_MASK. Though both of them contain the same numeric value of
0x3f, MAP_HUGE_MASK flag sounds more appropriate than the other one in
the context. Hence change it back.
Link: http://lkml.kernel.org/r/20170404045635.616-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tetsuo has reported that sysrq triggered OOM killer will print a
misleading information when no tasks are selected:
sysrq: SysRq : Manual OOM execution
Out of memory: Kill process 4468 ((agetty)) score 0 or sacrifice child
Killed process 4468 ((agetty)) total-vm:43704kB, anon-rss:1760kB, file-rss:0kB, shmem-rss:0kB
sysrq: SysRq : Manual OOM execution
Out of memory: Kill process 4469 (systemd-cgroups) score 0 or sacrifice child
Killed process 4469 (systemd-cgroups) total-vm:10704kB, anon-rss:120kB, file-rss:0kB, shmem-rss:0kB
sysrq: SysRq : Manual OOM execution
sysrq: OOM request ignored because killer is disabled
sysrq: SysRq : Manual OOM execution
sysrq: OOM request ignored because killer is disabled
sysrq: SysRq : Manual OOM execution
sysrq: OOM request ignored because killer is disabled
The real reason is that there are no eligible tasks for the OOM killer
to select but since commit 7c5f64f84483 ("mm: oom: deduplicate victim
selection code for memcg and global oom") the semantic of out_of_memory
has changed without updating moom_callback.
This patch updates moom_callback to tell that no task was eligible which
is the case for both oom killer disabled and no eligible tasks. In
order to help distinguish first case from the second add printk to both
oom_killer_{enable,disable}. This information is useful on its own
because it might help debugging potential memory allocation failures.
Fixes: 7c5f64f84483 ("mm: oom: deduplicate victim selection code for memcg and global oom")
Link: http://lkml.kernel.org/r/20170404134705.6361-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Currently, selftest for userfaultfd is compiled three times: for
anonymous, shared and hugetlb memory. Let's combine all the cases into
a single executable which will have a command line option for selection
of the test type.
Link: http://lkml.kernel.org/r/1490869741-5913-1-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix variable name error in comments. No code changes.
Link: http://lkml.kernel.org/r/20170403161655.5081-1-haolee.swjtu@gmail.com
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add a warning diagnostics to user if we failed to allocate swap slots
cache and use it.
[akpm@linux-foundation.org: use WARN_ONCE return value, fix grammar in message]
Link: http://lkml.kernel.org/r/20170328234827.GA10107@linux.intel.com
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It is preferred, and the rest of migrate.h gets it right.
Link: http://lkml.kernel.org/r/1490336009-8024-1-git-send-email-pushkar.iit@gmail.com
Signed-off-by: Pushkar Jambhlekar <pushkar.iit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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On SPARSEMEM systems page poisoning is enabled after buddy is up,
because of the dependency on page extension init. This causes the pages
released by free_all_bootmem not to be poisoned. This either delays or
misses the identification of some issues because the pages have to
undergo another cycle of alloc-free-alloc for any corruption to be
detected.
Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON
flag. Since all the free pages will now be poisoned, the flag need not
be verified before checking the poison during an alloc.
[vinmenon@codeaurora.org: fix Kconfig]
Link: http://lkml.kernel.org/r/1490878002-14423-1-git-send-email-vinmenon@codeaurora.org
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Cluster lock is used to protect the swap_cluster_info and corresponding
elements in swap_info_struct->swap_map[]. But it is found that now in
scan_swap_map_slots(), swap_avail_lock may be acquired when cluster lock
is held. This does no good except making the locking more complex and
improving the potential locking contention, because the
swap_info_struct->lock is used to protect the data structure operated in
the code already. Fix this via moving the corresponding operations in
scan_swap_map_slots() out of cluster lock.
Link: http://lkml.kernel.org/r/20170317064635.12792-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is just a cleanup patch, no functionality change.
In cluster_list_add_tail(), spin_lock_nested() is used to lock the
cluster, while unlock_cluster() is used to unlock the cluster. To
improve the code readability, use spin_unlock() directly to unlock the
cluster.
Link: http://lkml.kernel.org/r/20170317064635.12792-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit cbab0e4eec29 ("swap: avoid read_swap_cache_async() race to
deadlock while waiting on discard I/O completion") fixed a deadlock in
read_swap_cache_async(). Because at that time, in swap allocation path,
a swap entry may be set as SWAP_HAS_CACHE, then wait for discarding to
complete before the page for the swap entry is added to the swap cache.
But in commit 815c2c543d3a ("swap: make swap discard async"), the
discarding for swap become asynchronous, waiting for discarding to
complete will be done before the swap entry is set as SWAP_HAS_CACHE.
So the comments in code is incorrect now. This patch fixes the
comments.
The cond_resched() added in the commit cbab0e4eec29 is not necessary now
too. But if we added some sleep in swap allocation path in the future,
there may be some hard to debug/reproduce deadlock bug. So it is kept.
Link: http://lkml.kernel.org/r/20170317064635.12792-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There is no user for it. Remove it.
[minchan@kernel.org: use false instead of SWAP_FAIL]
Link: http://lkml.kernel.org/r/20170316053313.GA19241@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-11-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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rmap_one's return value controls whether rmap_work should contine to
scan other ptes or not so it's target for changing to boolean. Return
true if the scan should be continued. Otherwise, return false to stop
the scanning.
This patch makes rmap_one's return value to boolean.
Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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There is no user of the return value from rmap_walk() and friends so
this patch makes them void-returning functions.
Link: http://lkml.kernel.org/r/1489555493-14659-9-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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try_to_unmap() returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for
boolean return. This patch changes it.
Link: http://lkml.kernel.org/r/1489555493-14659-8-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In 2002, [1] introduced SWAP_AGAIN. At that time, try_to_unmap_one used
spin_trylock(&mm->page_table_lock) so it's really easy to contend and
fail to hold a lock so SWAP_AGAIN to keep LRU status makes sense.
However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN so
remove SWAP_AGAIN and just return SWAP_FAIL.
[1] c48c43e, minimal rmap
Link: http://lkml.kernel.org/r/1489555493-14659-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ttu doesn't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL
because it means the page is not-swappable so it should move to another
LRU list(active or unevictable). putback friends will move it to right
list depending on the page's LRU flag.
Link: http://lkml.kernel.org/r/1489555493-14659-6-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped the page has
VM_LOCKED flag. In that time, VM set PG_mlocked to the page if the page
is not pte-mapped THP which cannot be mlocked, either.
With that, __munlock_isolated_page can use PageMlocked to check whether
try_to_munlock is successful or not without relying on try_to_munlock's
retval. It helps to make try_to_unmap/try_to_unmap_one simple with
upcoming patches.
[minchan@kernel.org: remove PG_Mlocked VM_BUG_ON check]
Link: http://lkml.kernel.org/r/20170411025615.GA6545@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-5-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
If the page is mapped and rescue in try_to_unmap_one, the
page_mapcount() of a page cannot be zero, so the page_mapcount check in
try_to_unmap is enough to return SWAP_SUCCESS. IOW, SWAP_MLOCK check is
redundant so remove it.
Link: http://lkml.kernel.org/r/1489555493-14659-4-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
If we found lazyfree page is dirty, try_to_unmap_one can just
SetPageSwapBakced in there like PG_mlocked page and just return with
SWAP_FAIL which is very natural because the page is not swappable right
now so that vmscan can activate it. There is no point to introduce new
return value SWAP_DIRTY in try_to_unmap at the moment.
Link: http://lkml.kernel.org/r/1489555493-14659-3-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Nobody uses ret variable. Remove it.
Link: http://lkml.kernel.org/r/1489555493-14659-2-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
By reviewing code, I find that when enter do_try_to_free_pages, the
may_thrash is always clear, and it will retry shrink zones to tap
cgroup's reserves memory by setting may_thrash when the former
shrink_zones reclaim nothing.
However, when memcg is disabled or on legacy hierarchy, or there do not
have any memcg protected by low limit, it should not do this useless
retry at all, for we do not have any cgroup's reserves memory to tap,
and we have already done hard work but made no progress, which as Michal
pointed out in former version, we are trying hard to control the retry
logical of page alloctor, and the current additional round of reclaim is
just lame.
Therefore, to avoid this unneeded retrying and make code more readable,
we remove the may_thrash field in scan_control, instead, introduce
memcg_low_reclaim and memcg_low_skipped, and only retry when
memcg_low_skipped, by setting memcg_low_reclaim.
[xieyisheng1@huawei.com: remove may_thrash field, introduce mem_cgroup_reclaim]
Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com
Link: http://lkml.kernel.org/r/1490191893-5923-1-git-send-email-ysxie@foxmail.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Suggested-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
By reviewing code, I find that if the migrate target is a large free
page and we ignore suitable, it may splite large target free page into
smaller block which is not good for defrag. So move the ignore block
suitable after check large free page.
As Vlastimil pointed out in RFC version that this patch is just based on
logical analyses which might be better for future-proofing the function
and it is most likely won't have any visible effect right now, for
direct compaction shouldn't have to be called if there's a
>=pageblock_order page already available.
Link: http://lkml.kernel.org/r/1489490743-5364-1-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The current implementation calculates usemap_size in two steps:
* calculate number of bytes to cover these bits
* calculate number of "unsigned long" to cover these bytes
It would be more clear by:
* calculate number of "unsigned long" to cover these bits
* multiple it with sizeof(unsigned long)
This patch refine usemap_size() a little to make it more easy to
understand.
Link: http://lkml.kernel.org/r/20170310043713.96871-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
__GFP_NOWARN, which is usually added to avoid warnings from callsites
that expect to fail and have fallbacks, currently also suppresses
allocation stall warnings. These trigger when an allocation is stuck
inside the allocator for 10 seconds or longer.
But there is no class of allocations that can get legitimately stuck in
the allocator for this long. This always indicates a problem.
Always emit stall warnings. Restrict __GFP_NOWARN to alloc failures.
Link: http://lkml.kernel.org/r/20170125181150.GA16398@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
kswapd is woken to reclaim a node based on a failed allocation request
from any eligible zone. Once reclaiming in balance_pgdat(), it will
continue reclaiming until there is an eligible zone available for the
zone it was woken for. kswapd tracks what zone it was recently woken
for in pgdat->kswapd_classzone_idx. If it has not been woken recently,
this zone will be 0.
However, the decision on whether to sleep is made on
kswapd_classzone_idx which is 0 without a recent wakeup request and that
classzone does not account for lowmem reserves. This allows kswapd to
sleep when a low small zone such as ZONE_DMA is balanced for a GFP_DMA
request even if a stream of allocations cannot use that zone. While
kswapd may be woken again shortly in the near future there are two
consequences -- the pgdat bits that control congestion are cleared
prematurely and direct reclaim is more likely as kswapd slept
prematurely.
This patch flips kswapd_classzone_idx to default to MAX_NR_ZONES (an
invalid index) when there has been no recent wakeups. If there are no
wakeups, it'll decide whether to sleep based on the highest possible
zone available (MAX_NR_ZONES - 1). It then becomes critical that the
"pgdat balanced" decisions during reclaim and when deciding to sleep are
the same. If there is a mismatch, kswapd can stay awake continually
trying to balance tiny zones.
simoop was used to evaluate it again. Two of the preparation patches
regressed the workload so they are included as the second set of
results. Otherwise this patch looks artifically excellent
4.11.0-rc1 4.11.0-rc1 4.11.0-rc1
vanilla clear-v2 keepawake-v2
Amean p50-Read 21670074.18 ( 0.00%) 19786774.76 ( 8.69%) 22668332.52 ( -4.61%)
Amean p95-Read 25456267.64 ( 0.00%) 24101956.27 ( 5.32%) 26738688.00 ( -5.04%)
Amean p99-Read 29369064.73 ( 0.00%) 27691872.71 ( 5.71%) 30991404.52 ( -5.52%)
Amean p50-Write 1390.30 ( 0.00%) 1011.91 ( 27.22%) 924.91 ( 33.47%)
Amean p95-Write 412901.57 ( 0.00%) 34874.98 ( 91.55%) 1362.62 ( 99.67%)
Amean p99-Write 6668722.09 ( 0.00%) 575449.60 ( 91.37%) 16854.04 ( 99.75%)
Amean p50-Allocation 78714.31 ( 0.00%) 84246.26 ( -7.03%) 74729.74 ( 5.06%)
Amean p95-Allocation 175533.51 ( 0.00%) 400058.43 (-127.91%) 101609.74 ( 42.11%)
Amean p99-Allocation 247003.02 ( 0.00%) 10905600.00 (-4315.17%) 125765.57 ( 49.08%)
With this patch on top, write and allocation latencies are massively
improved. The read latencies are slightly impaired but it's worth
noting that this is mostly due to the IO scheduler and not directly
related to reclaim. The vmstats are a bit of a mix but the relevant
ones are as follows;
4.10.0-rc7 4.10.0-rc7 4.10.0-rc7
mmots-20170209 clear-v1r25keepawake-v1r25
Swap Ins 0 0 0
Swap Outs 0 608 0
Direct pages scanned 6910672 3132699 6357298
Kswapd pages scanned 57036946 82488665 56986286
Kswapd pages reclaimed 55993488 63474329 55939113
Direct pages reclaimed 6905990 2964843 6352115
Kswapd efficiency 98% 76% 98%
Kswapd velocity 12494.375 17597.507 12488.065
Direct efficiency 99% 94% 99%
Direct velocity 1513.835 668.306 1393.148
Page writes by reclaim 0.000 4410243.000 0.000
Page writes file 0 4409635 0
Page writes anon 0 608 0
Page reclaim immediate 1036792 14175203 1042571
4.11.0-rc1 4.11.0-rc1 4.11.0-rc1
vanilla clear-v2 keepawake-v2
Swap Ins 0 12 0
Swap Outs 0 838 0
Direct pages scanned 6579706 3237270 6256811
Kswapd pages scanned 61853702 79961486 54837791
Kswapd pages reclaimed 60768764 60755788 53849586
Direct pages reclaimed 6579055 2987453 6256151
Kswapd efficiency 98% 75% 98%
Page writes by reclaim 0.000 4389496.000 0.000
Page writes file 0 4388658 0
Page writes anon 0 838 0
Page reclaim immediate 1073573 14473009 982507
Swap-outs are equivalent to baseline.
Direct reclaim is reduced but not eliminated. It's worth noting that
there are two periods of direct reclaim for this workload. The first is
when it switches from preparing the files for the actual test itself.
It's a lot of file IO followed by a lot of allocs that reclaims heavily
for a brief window. While direct reclaim is lower with clear-v2, it is
due to kswapd scanning aggressively and trying to reclaim the world
which is not the right thing to do. With the patches applied, there is
still direct reclaim but the phase change from "creating work files" to
starting multiple threads that allocate a lot of anonymous memory faster
than kswapd can reclaim.
Scanning/reclaim efficiency is restored by this patch.
Page writes from reclaim context are back at 0 which is ideal.
Pages immediately reclaimed after IO completes is slightly improved but
it is expected this will vary slightly.
On UMA, there is almost no change so this is not expected to be a
universal win.
[mgorman@suse.de: fix ->kswapd_classzone_idx initialization]
Link: http://lkml.kernel.org/r/20170406174538.5msrznj6nt6qpbx5@suse.de
Link: http://lkml.kernel.org/r/20170309075657.25121-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
A pgdat tracks if recent reclaim encountered too many dirty, writeback
or congested pages. The flags control whether kswapd writes pages back
from reclaim context, tags pages for immediate reclaim when IO
completes, whether processes block on wait_iff_congested and whether
kswapd blocks when too many pages marked for immediate reclaim are
encountered.
The state is cleared in a check function with side-effects. With the
patch "mm, vmscan: fix zone balance check in prepare_kswapd_sleep", the
timing of when the bits get cleared changed. Due to the way the check
works, it'll clear the bits if ZONE_DMA is balanced for a GFP_DMA
allocation because it does not account for lowmem reserves properly.
For the simoop workload, kswapd is not stalling when it should due to
the premature clearing, writing pages from reclaim context like crazy
and generally being unhelpful.
This patch resets the pgdat bits related to page reclaim only when
kswapd is going to sleep. The comparison with simoop is then
4.11.0-rc1 4.11.0-rc1 4.11.0-rc1
vanilla fixcheck-v2 clear-v2
Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%) 19786774.76 ( 8.69%)
Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%) 24101956.27 ( 5.32%)
Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%) 27691872.71 ( 5.71%)
Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%) 1011.91 ( 27.22%)
Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%) 34874.98 ( 91.55%)
Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%) 575449.60 ( 91.37%)
Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%) 84246.26 ( -7.03%)
Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%) 400058.43 (-127.91%)
Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%) 10905600.00 (-4315.17%)
Read latency is improved, write latency is mostly improved but
allocation latency is regressed. kswapd is still reclaiming
inefficiently, pages are being written back from writeback context and a
host of other issues. However, given the change, it needed to be
spelled out why the side-effect was moved.
Link: http://lkml.kernel.org/r/20170309075657.25121-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "Reduce amount of time kswapd sleeps prematurely", v2.
The series is unusual in that the first patch fixes one problem and
introduces other issues that are noted in the changelog. Patch 2 makes
a minor modification that is worth considering on its own but leaves the
kernel in a state where it behaves badly. It's not until patch 3 that
there is an improvement against baseline.
This was mostly motivated by examining Chris Mason's "simoop" benchmark
which puts the VM under similar pressure to HADOOP. It has been
reported that the benchmark has regressed severely during the last
number of releases. While I cannot reproduce all the same problems
Chris experienced due to hardware limitations, there was a number of
problems on a 2-socket machine with a single disk.
simoop latencies
4.11.0-rc1 4.11.0-rc1
vanilla keepawake-v2
Amean p50-Read 21670074.18 ( 0.00%) 22668332.52 ( -4.61%)
Amean p95-Read 25456267.64 ( 0.00%) 26738688.00 ( -5.04%)
Amean p99-Read 29369064.73 ( 0.00%) 30991404.52 ( -5.52%)
Amean p50-Write 1390.30 ( 0.00%) 924.91 ( 33.47%)
Amean p95-Write 412901.57 ( 0.00%) 1362.62 ( 99.67%)
Amean p99-Write 6668722.09 ( 0.00%) 16854.04 ( 99.75%)
Amean p50-Allocation 78714.31 ( 0.00%) 74729.74 ( 5.06%)
Amean p95-Allocation 175533.51 ( 0.00%) 101609.74 ( 42.11%)
Amean p99-Allocation 247003.02 ( 0.00%) 125765.57 ( 49.08%)
These are latencies. Read/write are threads reading fixed-size random
blocks from a simulated database. The allocation latency is mmaping and
faulting regions of memory. The p50, 95 and p99 reports the worst
latencies for 50% of the samples, 95% and 99% respectively.
For example, the report indicates that while the test was running 99% of
writes completed 99.75% faster. It's worth noting that on a UMA machine
that no difference in performance with simoop was observed so milage
will vary.
It's noted that there is a slight impact to read latencies but it's
mostly due to IO scheduler decisions and offset by the large reduction
in other latencies.
This patch (of 3):
The check in prepare_kswapd_sleep needs to match the one in
balance_pgdat since the latter will return as soon as any one of the
zones in the classzone is above the watermark. This is specially
important for higher order allocations since balance_pgdat will
typically reset the order to zero relying on compaction to create the
higher order pages. Without this patch, prepare_kswapd_sleep fails to
wake up kcompactd since the zone balance check fails.
It was first reported against 4.9.7 that kswapd is failing to wake up
kcompactd due to a mismatch in the zone balance check between
balance_pgdat() and prepare_kswapd_sleep().
balance_pgdat() returns as soon as a single zone satisfies the
allocation but prepare_kswapd_sleep() requires all zones to do +the
same. This causes prepare_kswapd_sleep() to never succeed except in the
order == 0 case and consequently, wakeup_kcompactd() is never called.
For the machine that originally motivated this patch, the state of
compaction from /proc/vmstat looked this way after a day and a half +of
uptime:
compact_migrate_scanned 240496
compact_free_scanned 76238632
compact_isolated 123472
compact_stall 1791
compact_fail 29
compact_success 1762
compact_daemon_wake 0
After applying the patch and about 10 hours of uptime the state looks
like this:
compact_migrate_scanned 59927299
compact_free_scanned 2021075136
compact_isolated 640926
compact_stall 4
compact_fail 2
compact_success 2
compact_daemon_wake 5160
Further notes from Mel that motivated him to pick this patch up and
resend it;
It was observed for the simoop workload (pressures the VM similar to
HADOOP) that kswapd was failing to keep ahead of direct reclaim. The
investigation noted that there was a need to rationalise kswapd
decisions to reclaim with kswapd decisions to sleep. With this patch on
a 2-socket box, there was a 49% reduction in direct reclaim scanning.
However, the impact otherwise is extremely negative. Kswapd reclaim
efficiency dropped from 98% to 76%. simoop has three latency-related
metrics for read, write and allocation (an anonymous mmap and fault).
4.11.0-rc1 4.11.0-rc1
vanilla fixcheck-v2
Amean p50-Read 21670074.18 ( 0.00%) 20464344.18 ( 5.56%)
Amean p95-Read 25456267.64 ( 0.00%) 25721423.64 ( -1.04%)
Amean p99-Read 29369064.73 ( 0.00%) 30174230.76 ( -2.74%)
Amean p50-Write 1390.30 ( 0.00%) 1395.28 ( -0.36%)
Amean p95-Write 412901.57 ( 0.00%) 37737.74 ( 90.86%)
Amean p99-Write 6668722.09 ( 0.00%) 666489.04 ( 90.01%)
Amean p50-Allocation 78714.31 ( 0.00%) 86286.22 ( -9.62%)
Amean p95-Allocation 175533.51 ( 0.00%) 351812.27 (-100.42%)
Amean p99-Allocation 247003.02 ( 0.00%) 6291171.56 (-2447.00%)
Of greater concern is that the patch causes swapping and page writes
from kswapd context rose from 0 pages to 4189753 pages during the hour
the workload ran for. By and large, the patch has very bad behaviour
but easily missed as the impact on a UMA machine is negligible.
This patch is included with the data in case a bisection leads to this
area. This patch is also a pre-requisite for the rest of the series.
Link: http://lkml.kernel.org/r/20170309075657.25121-2-mgorman@techsingularity.net
Signed-off-by: Shantanu Goel <sgoel01@yahoo.com>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
With the discussion[1], I found it seems there are every PageFlags
functions return bool at this moment so we don't need double negation
any more. Although it's not a problem to keep it, it makes future users
confused to use double negation for them, too.
Remove such possibility.
[1] https://marc.info/?l=linux-kernel&m=148881578820434
Frankly sepaking, I like every PageFlags to return bool instead of int.
It will make it clear. AFAIR, Chen Gang had tried it but don't know why
it was not merged at that time.
http://lkml.kernel.org/r/1469336184-1904-1-git-send-email-chengang@emindsoft.com.cn
Link: http://lkml.kernel.org/r/1488868597-32222-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Since commit 3ad38ceb2769 ("x86/mm: Remove CONFIG_DEBUG_NX_TEST"),
nothing is using the exported rodata_test_data variable, so drop the
export.
This additionally updates the pr_fmt to avoid redundant strings and
adjusts some whitespace.
Link: http://lkml.kernel.org/r/20170307005313.GA85809@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The round_up() macro generates a couple of unnecessary instructions
in this usage:
48cd: 49 8b 47 50 mov 0x50(%r15),%rax
48d1: 48 83 e8 01 sub $0x1,%rax
48d5: 48 0d ff 0f 00 00 or $0xfff,%rax
48db: 48 83 c0 01 add $0x1,%rax
48df: 48 c1 f8 0c sar $0xc,%rax
48e3: 48 39 c3 cmp %rax,%rbx
48e6: 72 2e jb 4916 <filemap_fault+0x96>
If we change round_up() to ((x) + __round_mask(x, y)) & ~__round_mask(x, y)
then GCC can see through it and remove the mask (because that would be
dead code given the subsequent shift):
48cd: 49 8b 47 50 mov 0x50(%r15),%rax
48d1: 48 05 ff 0f 00 00 add $0xfff,%rax
48d7: 48 c1 e8 0c shr $0xc,%rax
48db: 48 39 c3 cmp %rax,%rbx
48de: 72 2e jb 490e <filemap_fault+0x8e>
But that's problematic because we'd evaluate 'y' twice. Converting
round_up into an inline function prevents it from being used in other
definitions. The easiest thing to do is just change these three usages
of round_up to use DIV_ROUND_UP. Also add an unlikely() because GCC's
heuristic is wrong in this case.
Link: http://lkml.kernel.org/r/20170207192812.5281-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
kjournald2 is central to the transaction commit processing. As such any
potential allocation from this kernel thread has to be GFP_NOFS. Make
sure to mark the whole kernel thread GFP_NOFS by the memalloc_nofs_save.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170306131408.9828-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
now that we have memalloc_nofs_{save,restore} api we can mark the whole
transaction context as implicitly GFP_NOFS. All allocations will
automatically inherit GFP_NOFS this way. This means that we do not have
to mark any of those requests with GFP_NOFS and moreover all the
ext4_kv[mz]alloc(GFP_NOFS) are also safe now because even the hardcoded
GFP_KERNEL allocations deep inside the vmalloc will be NOFS now.
[akpm@linux-foundation.org: tweak comments]
Link: http://lkml.kernel.org/r/20170306131408.9828-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
API to prevent from reclaim recursion into the fs because vmalloc can
invoke unconditional GFP_KERNEL allocations and these functions might be
called from the NOFS contexts. The memalloc_noio_save will enforce
GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
unnecessary. Let's use memalloc_nofs_{save,restore} instead as it
should provide exactly what we need here - implicit GFP_NOFS context.
Link: http://lkml.kernel.org/r/20170306131408.9828-6-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
GFP_NOFS context is used for the following 5 reasons currently:
- to prevent from deadlocks when the lock held by the allocation
context would be needed during the memory reclaim
- to prevent from stack overflows during the reclaim because the
allocation is performed from a deep context already
- to prevent lockups when the allocation context depends on other
reclaimers to make a forward progress indirectly
- just in case because this would be safe from the fs POV
- silence lockdep false positives
Unfortunately overuse of this allocation context brings some problems to
the MM. Memory reclaim is much weaker (especially during heavy FS
metadata workloads), OOM killer cannot be invoked because the MM layer
doesn't have enough information about how much memory is freeable by the
FS layer.
In many cases it is far from clear why the weaker context is even used
and so it might be used unnecessarily. We would like to get rid of
those as much as possible. One way to do that is to use the flag in
scopes rather than isolated cases. Such a scope is declared when really
necessary, tracked per task and all the allocation requests from within
the context will simply inherit the GFP_NOFS semantic.
Not only this is easier to understand and maintain because there are
much less problematic contexts than specific allocation requests, this
also helps code paths where FS layer interacts with other layers (e.g.
crypto, security modules, MM etc...) and there is no easy way to convey
the allocation context between the layers.
Introduce memalloc_nofs_{save,restore} API to control the scope of
GFP_NOFS allocation context. This is basically copying
memalloc_noio_{save,restore} API we have for other restricted allocation
context GFP_NOIO. The PF_MEMALLOC_NOFS flag already exists and it is
just an alias for PF_FSTRANS which has been xfs specific until recently.
There are no more PF_FSTRANS users anymore so let's just drop it.
PF_MEMALLOC_NOFS is now checked in the MM layer and drops __GFP_FS
implicitly same as PF_MEMALLOC_NOIO drops __GFP_IO. memalloc_noio_flags
is renamed to current_gfp_context because it now cares about both
PF_MEMALLOC_NOFS and PF_MEMALLOC_NOIO contexts. Xfs code paths preserve
their semantic. kmem_flags_convert() doesn't need to evaluate the flag
anymore.
This patch shouldn't introduce any functional changes.
Let's hope that filesystems will drop direct GFP_NOFS (resp. ~__GFP_FS)
usage as much as possible and only use a properly documented
memalloc_nofs_{save,restore} checkpoints where they are appropriate.
[akpm@linux-foundation.org: fix comment typo, reflow comment]
Link: http://lkml.kernel.org/r/20170306131408.9828-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
xfs has defined PF_FSTRANS to declare a scope GFP_NOFS semantic quite
some time ago. We would like to make this concept more generic and use
it for other filesystems as well. Let's start by giving the flag a more
generic name PF_MEMALLOC_NOFS which is in line with an exiting
PF_MEMALLOC_NOIO already used for the same purpose for GFP_NOIO
contexts. Replace all PF_FSTRANS usage from the xfs code in the first
step before we introduce a full API for it as xfs uses the flag directly
anyway.
This patch doesn't introduce any functional change.
Link: http://lkml.kernel.org/r/20170306131408.9828-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The current implementation of the reclaim lockup detection can lead to
false positives and those even happen and usually lead to tweak the code
to silence the lockdep by using GFP_NOFS even though the context can use
__GFP_FS just fine.
See
http://lkml.kernel.org/r/20160512080321.GA18496@dastard
as an example.
=================================
[ INFO: inconsistent lock state ]
4.5.0-rc2+ #4 Tainted: G O
---------------------------------
inconsistent {RECLAIM_FS-ON-R} -> {IN-RECLAIM_FS-W} usage.
kswapd0/543 [HC0[0]:SC0[0]:HE1:SE1] takes:
(&xfs_nondir_ilock_class){++++-+}, at: xfs_ilock+0x177/0x200 [xfs]
{RECLAIM_FS-ON-R} state was registered at:
mark_held_locks+0x79/0xa0
lockdep_trace_alloc+0xb3/0x100
kmem_cache_alloc+0x33/0x230
kmem_zone_alloc+0x81/0x120 [xfs]
xfs_refcountbt_init_cursor+0x3e/0xa0 [xfs]
__xfs_refcount_find_shared+0x75/0x580 [xfs]
xfs_refcount_find_shared+0x84/0xb0 [xfs]
xfs_getbmap+0x608/0x8c0 [xfs]
xfs_vn_fiemap+0xab/0xc0 [xfs]
do_vfs_ioctl+0x498/0x670
SyS_ioctl+0x79/0x90
entry_SYSCALL_64_fastpath+0x12/0x6f
CPU0
----
lock(&xfs_nondir_ilock_class);
<Interrupt>
lock(&xfs_nondir_ilock_class);
*** DEADLOCK ***
3 locks held by kswapd0/543:
stack backtrace:
CPU: 0 PID: 543 Comm: kswapd0 Tainted: G O 4.5.0-rc2+ #4
Call Trace:
lock_acquire+0xd8/0x1e0
down_write_nested+0x5e/0xc0
xfs_ilock+0x177/0x200 [xfs]
xfs_reflink_cancel_cow_range+0x150/0x300 [xfs]
xfs_fs_evict_inode+0xdc/0x1e0 [xfs]
evict+0xc5/0x190
dispose_list+0x39/0x60
prune_icache_sb+0x4b/0x60
super_cache_scan+0x14f/0x1a0
shrink_slab.part.63.constprop.79+0x1e9/0x4e0
shrink_zone+0x15e/0x170
kswapd+0x4f1/0xa80
kthread+0xf2/0x110
ret_from_fork+0x3f/0x70
To quote Dave:
"Ignoring whether reflink should be doing anything or not, that's a
"xfs_refcountbt_init_cursor() gets called both outside and inside
transactions" lockdep false positive case. The problem here is lockdep
has seen this allocation from within a transaction, hence a GFP_NOFS
allocation, and now it's seeing it in a GFP_KERNEL context. Also note
that we have an active reference to this inode.
So, because the reclaim annotations overload the interrupt level
detections and it's seen the inode ilock been taken in reclaim
("interrupt") context, this triggers a reclaim context warning where
it thinks it is unsafe to do this allocation in GFP_KERNEL context
holding the inode ilock..."
This sounds like a fundamental problem of the reclaim lock detection.
It is really impossible to annotate such a special usecase IMHO unless
the reclaim lockup detection is reworked completely. Until then it is
much better to provide a way to add "I know what I am doing flag" and
mark problematic places. This would prevent from abusing GFP_NOFS flag
which has a runtime effect even on configurations which have lockdep
disabled.
Introduce __GFP_NOLOCKDEP flag which tells the lockdep gfp tracking to
skip the current allocation request.
While we are at it also make sure that the radix tree doesn't
accidentaly override tags stored in the upper part of the gfp_mask.
Link: http://lkml.kernel.org/r/20170306131408.9828-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "scope GFP_NOFS api", v5.
This patch (of 7):
Commit 21caf2fc1931 ("mm: teach mm by current context info to not do I/O
during memory allocation") added the memalloc_noio_(save|restore)
functions to enable people to modify the MM behavior by disabling I/O
during memory allocation.
This was further extended in commit 934f3072c17c ("mm: clear __GFP_FS
when PF_MEMALLOC_NOIO is set").
memalloc_noio_* functions prevent allocation paths recursing back into
the filesystem without explicitly changing the flags for every
allocation site.
However, lockdep hasn't been keeping up with the changes and it entirely
misses handling the memalloc_noio adjustments. Instead, it is left to
the callers of __lockdep_trace_alloc to call the function after they
have shaven the respective GFP flags which can lead to false positives:
=================================
[ INFO: inconsistent lock state ]
4.10.0-nbor #134 Not tainted
---------------------------------
inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
fsstress/3365 [HC0[0]:SC0[0]:HE1:SE1] takes:
(&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230
{IN-RECLAIM_FS-W} state was registered at:
__lock_acquire+0x62a/0x17c0
lock_acquire+0xc5/0x220
down_write_nested+0x4f/0x90
xfs_ilock+0x141/0x230
xfs_reclaim_inode+0x12a/0x320
xfs_reclaim_inodes_ag+0x2c8/0x4e0
xfs_reclaim_inodes_nr+0x33/0x40
xfs_fs_free_cached_objects+0x19/0x20
super_cache_scan+0x191/0x1a0
shrink_slab+0x26f/0x5f0
shrink_node+0xf9/0x2f0
kswapd+0x356/0x920
kthread+0x10c/0x140
ret_from_fork+0x31/0x40
irq event stamp: 173777
hardirqs last enabled at (173777): __local_bh_enable_ip+0x70/0xc0
hardirqs last disabled at (173775): __local_bh_enable_ip+0x37/0xc0
softirqs last enabled at (173776): _xfs_buf_find+0x67a/0xb70
softirqs last disabled at (173774): _xfs_buf_find+0x5db/0xb70
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&xfs_nondir_ilock_class);
<Interrupt>
lock(&xfs_nondir_ilock_class);
*** DEADLOCK ***
4 locks held by fsstress/3365:
#0: (sb_writers#10){++++++}, at: mnt_want_write+0x24/0x50
#1: (&sb->s_type->i_mutex_key#12){++++++}, at: vfs_setxattr+0x6f/0xb0
#2: (sb_internal#2){++++++}, at: xfs_trans_alloc+0xfc/0x140
#3: (&xfs_nondir_ilock_class){++++?.}, at: xfs_ilock+0x141/0x230
stack backtrace:
CPU: 0 PID: 3365 Comm: fsstress Not tainted 4.10.0-nbor #134
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
kmem_cache_alloc_node_trace+0x3a/0x2c0
vm_map_ram+0x2a1/0x510
_xfs_buf_map_pages+0x77/0x140
xfs_buf_get_map+0x185/0x2a0
xfs_attr_rmtval_set+0x233/0x430
xfs_attr_leaf_addname+0x2d2/0x500
xfs_attr_set+0x214/0x420
xfs_xattr_set+0x59/0xb0
__vfs_setxattr+0x76/0xa0
__vfs_setxattr_noperm+0x5e/0xf0
vfs_setxattr+0xae/0xb0
setxattr+0x15e/0x1a0
path_setxattr+0x8f/0xc0
SyS_lsetxattr+0x11/0x20
entry_SYSCALL_64_fastpath+0x23/0xc6
Let's fix this by making lockdep explicitly do the shaving of respective
GFP flags.
Fixes: 934f3072c17c ("mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set")
Link: http://lkml.kernel.org/r/20170306131408.9828-2-mhocko@kernel.org
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
After "mm, vmstat: print non-populated zones in zoneinfo",
/proc/zoneinfo will show unpopulated zones.
The per-cpu pageset statistics are not relevant for unpopulated zones
and can be potentially lengthy, so supress them when they are not
interesting.
Also moves lowmem reserve protection information above pcp stats since
it is relevant for all zones per vm.lowmem_reserve_ratio.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703061400500.46428@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Initscripts can use the information (protection levels) from
/proc/zoneinfo to configure vm.lowmem_reserve_ratio at boot.
vm.lowmem_reserve_ratio is an array of ratios for each configured zone
on the system. If a zone is not populated on an arch, /proc/zoneinfo
suppresses its output.
This results in there not being a 1:1 mapping between the set of zones
emitted by /proc/zoneinfo and the zones configured by
vm.lowmem_reserve_ratio.
This patch shows statistics for non-populated zones in /proc/zoneinfo.
The zones exist and hold a spot in the vm.lowmem_reserve_ratio array.
Without this patch, it is not possible to determine which index in the
array controls which zone if one or more zones on the system are not
populated.
Remaining users of walk_zones_in_node() are unchanged. Files such as
/proc/pagetypeinfo require certain zone data to be initialized properly
for display, which is not done for unpopulated zones.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1703031451310.98023@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Use is_migrate_isolate_page() to simplify the code, no functional
changes.
Link: http://lkml.kernel.org/r/58B94FB1.8020802@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Introduce two helpers, is_migrate_highatomic() and is_migrate_highatomic_page().
Simplify the code, no functional changes.
[akpm@linux-foundation.org: use static inlines rather than macros, per mhocko]
Link: http://lkml.kernel.org/r/58B94F15.6060606@huawei.com
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Before using cluster lock in free_swap_and_cache(), the
swap_info_struct->lock will be held during freeing the swap entry and
acquiring page lock, so the page swap count will not change when testing
page information later. But after using cluster lock, the cluster lock
(or swap_info_struct->lock) will be held only during freeing the swap
entry. So before acquiring the page lock, the page swap count may be
changed in another thread. If the page swap count is not 0, we should
not delete the page from the swap cache. This is fixed via checking
page swap count again after acquiring the page lock.
I found the race when I review the code, so I didn't trigger the race
via a test program. If the race occurs for an anonymous page shared by
multiple processes via fork, multiple pages will be allocated and
swapped in from the swap device for the previously shared one page.
That is, the user-visible runtime effect is more memory will be used and
the access latency for the page will be higher, that is, the performance
regression.
Link: http://lkml.kernel.org/r/20170301143905.12846-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
