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No functional change.
Link: http://lkml.kernel.org/r/20190118235123.27843-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Move the PAGE_OWNER option from submenu "Compile-time checks and
compiler options" to dedicated submenu "Memory Debugging".
Link: http://lkml.kernel.org/r/20190120024254.6270-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
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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The variable 'addr' is redundant in arch_get_unmapped_area_topdown(),
just use parameter 'addr0' directly. Then remove the const qualifier of
the parameter, and change its name to 'addr'.
And in according with other functions, remove the const qualifier of all
other no-pointer parameters in function arch_get_unmapped_area_topdown().
Link: http://lkml.kernel.org/r/20190127041112.25599-1-nullptr.cpp@gmail.com
Signed-off-by: Yang Fan <nullptr.cpp@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since the start of the git history of Linux, the kernel after selecting
the worst process to be oom-killed, prefer to kill its child (if the
child does not share mm with the parent). Later it was changed to
prefer to kill a child who is worst. If the parent is still the worst
then the parent will be killed.
This heuristic assumes that the children did less work than their parent
and by killing one of them, the work lost will be less. However this is
very workload dependent. If there is a workload which can benefit from
this heuristic, can use oom_score_adj to prefer children to be killed
before the parent.
The select_bad_process() has already selected the worst process in the
system/memcg. There is no need to recheck the badness of its children
and hoping to find a worse candidate. That's a lot of unneeded racy
work. Also the heuristic is dangerous because it make fork bomb like
workloads to recover much later because we constantly pick and kill
processes which are not memory hogs. So, let's remove this whole
heuristic.
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20190121215850.221745-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
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>
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When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
Link: http://lkml.kernel.org/r/20190122152151.16139-14-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Laura Abbott <labbott@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pages which use page_type must never be mapped to userspace as it would
destroy their page type. Add an explicit check for this instead of
assuming that kernel drivers always get this right.
Link: http://lkml.kernel.org/r/20190129053830.3749-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It's never appropriate to map a page allocated by SLAB into userspace.
A buggy device driver might try this, or an attacker might be able to
find a way to make it happen.
Christoph said:
: Let's just fail the code. Currently this may work with SLUB. But SLAB
: and SLOB overlay fields with mapcount. So you would have a corrupted page
: struct if you mapped a slab page to user space.
Link: http://lkml.kernel.org/r/20190125173827.2658-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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One of the vmalloc stress test case triggers the kernel BUG():
<snip>
[60.562151] ------------[ cut here ]------------
[60.562154] kernel BUG at mm/vmalloc.c:512!
[60.562206] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[60.562247] CPU: 0 PID: 430 Comm: vmalloc_test/0 Not tainted 4.20.0+ #161
[60.562293] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[60.562351] RIP: 0010:alloc_vmap_area+0x36f/0x390
<snip>
it can happen due to big align request resulting in overflowing of
calculated address, i.e. it becomes 0 after ALIGN()'s fixup.
Fix it by checking if calculated address is within vstart/vend range.
Link: http://lkml.kernel.org/r/20190124115648.9433-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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memcg has a significant number of files exposed to kernfs where their
value is either exposed directly or is "max" in the case of
PAGE_COUNTER_MAX.
This patch makes this generic by providing a single function to do this
work. In combination with the previous patch adding
mem_cgroup_from_seq, this makes all of the seq_show feeder functions
significantly more simple.
Link: http://lkml.kernel.org/r/20190124194100.GA31425@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.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 the start of a series of patches similar to my earlier
DEFINE_MEMCG_MAX_OR_VAL work, but with less Macro Magic(tm).
There are a bunch of places we go from seq_file to mem_cgroup, which
currently requires manually getting the css, then getting the mem_cgroup
from the css. It's in enough places now that having mem_cgroup_from_seq
makes sense (and also makes the next patch a bit nicer).
Link: http://lkml.kernel.org/r/20190124194050.GA31341@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Compaction is inherently race-prone as a suitable page freed during
compaction can be allocated by any parallel task. This patch uses a
capture_control structure to isolate a page immediately when it is freed
by a direct compactor in the slow path of the page allocator. The
intent is to avoid redundant scanning.
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%)
Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%)
Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%)
Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%)
Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%)
Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%*
Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%)
Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%)
Latency is only moderately affected but the devil is in the details. A
closer examination indicates that base page fault latency is reduced but
latency of huge pages is increased as it takes creater care to succeed.
Part of the "problem" is that allocation success rates are close to 100%
even when under pressure and compaction gets harder
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%)
Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%)
Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%)
Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%)
Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%)
Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%)
Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%)
Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%)
And scan rates are reduced as expected by 6% for the migration scanner
and 29% for the free scanner indicating that there is less redundant
work.
Compaction migrate scanned 20815362 19573286
Compaction free scanned 16352612 11510663
[mgorman@techsingularity.net: remove redundant check]
Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net
Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pageblock hints are cleared when compaction restarts or kswapd makes
enough progress that it can sleep but it's over-eager in that the bit is
cleared for migration sources with no LRU pages and migration targets
with no free pages. As pageblock skip hint flushes are relatively rare
and out-of-band with respect to kswapd, this patch makes a few more
expensive checks to see if it's appropriate to even clear the bit.
Every pageblock that is not cleared will avoid 512 pages being scanned
unnecessarily on x86-64.
The impact is variable with different workloads showing small
differences in latency, success rates and scan rates. This is expected
as clearing the hints is not that common but doing a small amount of
work out-of-band to avoid a large amount of work in-band later is
generally a good thing.
Link: http://lkml.kernel.org/r/20190118175136.31341-22-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
[cai@lca.pw: no stuck in __reset_isolation_pfn()]
Link: http://lkml.kernel.org/r/20190206034732.75687-1-cai@lca.pw
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Once fast searching finishes, there is a possibility that the linear
scanner is scanning full blocks found by the fast scanner earlier. This
patch uses an adaptive stride to sample pageblocks for free pages. The
more consecutive full pageblocks encountered, the larger the stride
until a pageblock with free pages is found. The scanners might meet
slightly sooner but it is an acceptable risk given that the search of
the free lists may still encounter the pages and adjust the cached PFN
of the free scanner accordingly.
5.0.0-rc1 5.0.0-rc1
roundrobin-v3r17 samplefree-v3r17
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2752.37 ( 0.00%) 2729.95 ( 0.81%)
Amean fault-both-5 4341.69 ( 0.00%) 4397.80 ( -1.29%)
Amean fault-both-7 6308.75 ( 0.00%) 6097.61 ( 3.35%)
Amean fault-both-12 10241.81 ( 0.00%) 9407.15 ( 8.15%)
Amean fault-both-18 13736.09 ( 0.00%) 10857.63 * 20.96%*
Amean fault-both-24 16853.95 ( 0.00%) 13323.24 * 20.95%*
Amean fault-both-30 15862.61 ( 0.00%) 17345.44 ( -9.35%)
Amean fault-both-32 18450.85 ( 0.00%) 16892.00 ( 8.45%)
The latency is mildly improved offseting some overhead from earlier
patches that are prerequisites for the rest of the series. However, a
major impact is on the free scan rate with an 82% reduction.
5.0.0-rc1 5.0.0-rc1
roundrobin-v3r17 samplefree-v3r17
Compaction migrate scanned 21607271 20116887
Compaction free scanned 95336406 16668703
It's also the first time in the series where the number of pages scanned
by the migration scanner is greater than the free scanner due to the
increased search efficiency.
Link: http://lkml.kernel.org/r/20190118175136.31341-21-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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target
As compaction proceeds and creates high-order blocks, the free list
search gets less efficient as the larger blocks are used as compaction
targets. Eventually, the larger blocks will be behind the migration
scanner for partially migrated pageblocks and the search fails. This
patch round-robins what orders are searched so that larger blocks can be
ignored and find smaller blocks that can be used as migration targets.
The overall impact was small on 1-socket but it avoids corner cases
where the migration/free scanners meet prematurely or situations where
many of the pageblocks encountered by the free scanner are almost full
instead of being properly packed. Previous testing had indicated that
without this patch there were occasional large spikes in the free
scanner without this patch.
[dan.carpenter@oracle.com: fix static checker warning]
Link: http://lkml.kernel.org/r/20190118175136.31341-20-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The fast isolation of free pages allows the cached PFN of the free
scanner to advance faster than necessary depending on the contents of
the free list. The key is that fast_isolate_freepages() can update
zone->compact_cached_free_pfn via isolate_freepages_block(). When the
fast search fails, the linear scan can start from a point that has
skipped valid migration targets, particularly pageblocks with just
low-order free pages. This can cause the migration source/target
scanners to meet prematurely causing a reset.
This patch starts by avoiding an update of the pageblock skip
information and cached PFN from isolate_freepages_block() and puts the
responsibility of updating that information in the callers. The fast
scanner will update the cached PFN if and only if it finds a block that
is higher than the existing cached PFN and sets the skip if the
pageblock is full or nearly full. The linear scanner will update
skipped information and the cached PFN only when a block is completely
scanned. The total impact is that the free scanner advances more slowly
as it is primarily driven by the linear scanner instead of the fast
search.
5.0.0-rc1 5.0.0-rc1
noresched-v3r17 slowfree-v3r17
Amean fault-both-3 2965.68 ( 0.00%) 3036.75 ( -2.40%)
Amean fault-both-5 3995.90 ( 0.00%) 4522.24 * -13.17%*
Amean fault-both-7 5842.12 ( 0.00%) 6365.35 ( -8.96%)
Amean fault-both-12 9550.87 ( 0.00%) 10340.93 ( -8.27%)
Amean fault-both-18 13304.72 ( 0.00%) 14732.46 ( -10.73%)
Amean fault-both-24 14618.59 ( 0.00%) 16288.96 ( -11.43%)
Amean fault-both-30 16650.96 ( 0.00%) 16346.21 ( 1.83%)
Amean fault-both-32 17145.15 ( 0.00%) 19317.49 ( -12.67%)
The impact to latency is higher than the last version but it appears to
be due to a slight increase in the free scan rates which is a potential
side-effect of the patch. However, this is necessary for later patches
that are more careful about how pageblocks are treated as earlier
iterations of those patches hit corner cases where the restarts were
punishing and very visible.
Link: http://lkml.kernel.org/r/20190118175136.31341-19-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Scanning on large machines can take a considerable length of time and
eventually need to be rescheduled. This is treated as an abort event
but that's not appropriate as the attempt is likely to be retried after
making numerous checks and taking another cycle through the page
allocator. This patch will check the need to reschedule if necessary
but continue the scanning.
The main benefit is reduced scanning when compaction is taking a long
time or the machine is over-saturated. It also avoids an unnecessary
exit of compaction that ends up being retried by the page allocator in
the outer loop.
5.0.0-rc1 5.0.0-rc1
synccached-v3r16 noresched-v3r17
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2958.27 ( 0.00%) 2965.68 ( -0.25%)
Amean fault-both-5 4091.90 ( 0.00%) 3995.90 ( 2.35%)
Amean fault-both-7 5803.05 ( 0.00%) 5842.12 ( -0.67%)
Amean fault-both-12 9481.06 ( 0.00%) 9550.87 ( -0.74%)
Amean fault-both-18 14141.51 ( 0.00%) 13304.72 ( 5.92%)
Amean fault-both-24 16438.00 ( 0.00%) 14618.59 ( 11.07%)
Amean fault-both-30 17531.72 ( 0.00%) 16650.96 ( 5.02%)
Amean fault-both-32 17101.96 ( 0.00%) 17145.15 ( -0.25%)
Link: http://lkml.kernel.org/r/20190118175136.31341-18-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With incremental changes, compact_should_abort no longer makes any
documented sense. Rename to compact_check_resched and update the
associated comments. There is no benefit other than reducing redundant
code and making the intent slightly clearer. It could potentially be
merged with earlier patches but it just makes the review slightly
harder.
Link: http://lkml.kernel.org/r/20190118175136.31341-17-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Migrate has separate cached PFNs for ASYNC and SYNC* migration on the
basis that some migrations will fail in ASYNC mode. However, if the
cached PFNs match at the start of scanning and pageblocks are skipped
due to having no isolation candidates, then the sync state does not
matter. This patch keeps matching cached PFNs in sync until a pageblock
with isolation candidates is found.
The actual benefit is marginal given that the sync scanner following the
async scanner will often skip a number of pageblocks but it's useless
work. Any benefit depends heavily on whether the scanners restarted
recently.
Link: http://lkml.kernel.org/r/20190118175136.31341-16-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When scanning for sources or targets, PageCompound is checked for huge
pages as they can be skipped quickly but it happens relatively late
after a lot of setup and checking. This patch short-cuts the check to
make it earlier. It might still change when the lock is acquired but
this has less overhead overall. The free scanner advances but the
migration scanner does not. Typically the free scanner encounters more
movable blocks that change state over the lifetime of the system and
also tends to scan more aggressively as it's actively filling its
portion of the physical address space with data. This could change in
the future but for the moment, this worked better in practice and
incurred fewer scan restarts.
The impact on latency and allocation success rates is marginal but the
free scan rates are reduced by 15% and system CPU usage is reduced by
3.3%. The 2-socket results are not materially different.
Link: http://lkml.kernel.org/r/20190118175136.31341-15-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Async migration aborts on spinlock contention but contention can be high
when there are multiple compaction attempts and kswapd is active. The
consequence is that the migration scanners move forward uselessly while
still contending on locks for longer while leaving suitable migration
sources behind.
This patch will acquire the lock but track when contention occurs. When
it does, the current pageblock will finish as compaction may succeed for
that block and then abort. This will have a variable impact on latency
as in some cases useless scanning is avoided (reduces latency) but a
lock will be contended (increase latency) or a single contended
pageblock is scanned that would otherwise have been skipped (increase
latency).
5.0.0-rc1 5.0.0-rc1
norescan-v3r16 finishcontend-v3r16
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 3002.07 ( 0.00%) 3153.17 ( -5.03%)
Amean fault-both-5 4684.47 ( 0.00%) 4280.52 ( 8.62%)
Amean fault-both-7 6815.54 ( 0.00%) 5811.50 * 14.73%*
Amean fault-both-12 10864.02 ( 0.00%) 9276.85 ( 14.61%)
Amean fault-both-18 12247.52 ( 0.00%) 11032.67 ( 9.92%)
Amean fault-both-24 15683.99 ( 0.00%) 14285.70 ( 8.92%)
Amean fault-both-30 18620.02 ( 0.00%) 16293.76 * 12.49%*
Amean fault-both-32 19250.28 ( 0.00%) 16721.02 * 13.14%*
5.0.0-rc1 5.0.0-rc1
norescan-v3r16 finishcontend-v3r16
Percentage huge-1 0.00 ( 0.00%) 0.00 ( 0.00%)
Percentage huge-3 95.00 ( 0.00%) 96.82 ( 1.92%)
Percentage huge-5 94.22 ( 0.00%) 95.40 ( 1.26%)
Percentage huge-7 92.35 ( 0.00%) 95.92 ( 3.86%)
Percentage huge-12 91.90 ( 0.00%) 96.73 ( 5.25%)
Percentage huge-18 89.58 ( 0.00%) 96.77 ( 8.03%)
Percentage huge-24 90.03 ( 0.00%) 96.05 ( 6.69%)
Percentage huge-30 89.14 ( 0.00%) 96.81 ( 8.60%)
Percentage huge-32 90.58 ( 0.00%) 97.41 ( 7.54%)
There is a variable impact that is mostly good on latency while allocation
success rates are slightly higher. System CPU usage is reduced by about
10% but scan rate impact is mixed
Compaction migrate scanned 27997659.00 20148867
Compaction free scanned 120782791.00 118324914
Migration scan rates are reduced 28% which is expected as a pageblock is
used by the async scanner instead of skipped. The impact on the free
scanner is known to be variable. Overall the primary justification for
this patch is that completing scanning of a pageblock is very important
for later patches.
[yuehaibing@huawei.com: fix unused variable warning]
Link: http://lkml.kernel.org/r/20190118175136.31341-14-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Pageblocks are marked for skip when no pages are isolated after a scan.
However, it's possible to hit corner cases where the migration scanner
gets stuck near the boundary between the source and target scanner. Due
to pages being migrated in blocks of COMPACT_CLUSTER_MAX, pages that are
migrated can be reallocated before the pageblock is complete. The
pageblock is not necessarily skipped so it can be rescanned multiple
times. Similarly, a pageblock with some dirty/writeback pages may fail
to migrate and be rescanned until writeback completes which is wasteful.
This patch tracks if a pageblock is being rescanned. If so, then the
entire pageblock will be migrated as one operation. This narrows the
race window during which pages can be reallocated during migration.
Secondly, if there are pages that cannot be isolated then the pageblock
will still be fully scanned and marked for skipping. On the second
rescan, the pageblock skip is set and the migration scanner makes
progress.
5.0.0-rc1 5.0.0-rc1
findfree-v3r16 norescan-v3r16
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 3200.68 ( 0.00%) 3002.07 ( 6.21%)
Amean fault-both-5 4847.75 ( 0.00%) 4684.47 ( 3.37%)
Amean fault-both-7 6658.92 ( 0.00%) 6815.54 ( -2.35%)
Amean fault-both-12 11077.62 ( 0.00%) 10864.02 ( 1.93%)
Amean fault-both-18 12403.97 ( 0.00%) 12247.52 ( 1.26%)
Amean fault-both-24 15607.10 ( 0.00%) 15683.99 ( -0.49%)
Amean fault-both-30 18752.27 ( 0.00%) 18620.02 ( 0.71%)
Amean fault-both-32 21207.54 ( 0.00%) 19250.28 * 9.23%*
5.0.0-rc1 5.0.0-rc1
findfree-v3r16 norescan-v3r16
Percentage huge-3 96.86 ( 0.00%) 95.00 ( -1.91%)
Percentage huge-5 93.72 ( 0.00%) 94.22 ( 0.53%)
Percentage huge-7 94.31 ( 0.00%) 92.35 ( -2.08%)
Percentage huge-12 92.66 ( 0.00%) 91.90 ( -0.82%)
Percentage huge-18 91.51 ( 0.00%) 89.58 ( -2.11%)
Percentage huge-24 90.50 ( 0.00%) 90.03 ( -0.52%)
Percentage huge-30 91.57 ( 0.00%) 89.14 ( -2.65%)
Percentage huge-32 91.00 ( 0.00%) 90.58 ( -0.46%)
Negligible difference but this was likely a case when the specific
corner case was not hit. A previous run of the same patch based on an
earlier iteration of the series showed large differences where migration
rates could be halved when the corner case was hit.
The specific corner case where migration scan rates go through the roof
was due to a dirty/writeback pageblock located at the boundary of the
migration/free scanner did not happen in this case. When it does
happen, the scan rates multipled by massive margins.
Link: http://lkml.kernel.org/r/20190118175136.31341-13-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Similar to the migration scanner, this patch uses the free lists to
quickly locate a migration target. The search is different in that
lower orders will be searched for a suitable high PFN if necessary but
the search is still bound. This is justified on the grounds that the
free scanner typically scans linearly much more than the migration
scanner.
If a free page is found, it is isolated and compaction continues if
enough pages were isolated. For SYNC* scanning, the full pageblock is
scanned for any remaining free pages so that is can be marked for
skipping in the near future.
1-socket thpfioscale
5.0.0-rc1 5.0.0-rc1
isolmig-v3r15 findfree-v3r16
Amean fault-both-3 3024.41 ( 0.00%) 3200.68 ( -5.83%)
Amean fault-both-5 4749.30 ( 0.00%) 4847.75 ( -2.07%)
Amean fault-both-7 6454.95 ( 0.00%) 6658.92 ( -3.16%)
Amean fault-both-12 10324.83 ( 0.00%) 11077.62 ( -7.29%)
Amean fault-both-18 12896.82 ( 0.00%) 12403.97 ( 3.82%)
Amean fault-both-24 13470.60 ( 0.00%) 15607.10 * -15.86%*
Amean fault-both-30 17143.99 ( 0.00%) 18752.27 ( -9.38%)
Amean fault-both-32 17743.91 ( 0.00%) 21207.54 * -19.52%*
The impact on latency is variable but the search is optimistic and
sensitive to the exact system state. Success rates are similar but the
major impact is to the rate of scanning
5.0.0-rc1 5.0.0-rc1
isolmig-v3r15 findfree-v3r16
Compaction migrate scanned 25646769 29507205
Compaction free scanned 201558184 100359571
The free scan rates are reduced by 50%. The 2-socket reductions for the
free scanner are more dramatic which is a likely reflection that the
machine has more memory.
[dan.carpenter@oracle.com: fix static checker warning]
[vbabka@suse.cz: correct number of pages scanned for lower orders]
Link: http://lkml.kernel.org/r/20190118175136.31341-12-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Due to either a fast search of the free list or a linear scan, it is
possible for multiple compaction instances to pick the same pageblock
for migration. This is lucky for one scanner and increased scanning for
all the others. It also allows a race between requests on which first
allocates the resulting free block.
This patch tests and updates the pageblock skip for the migration
scanner carefully. When isolating a block, it will check and skip if
the block is already in use. Once the zone lock is acquired, it will be
rechecked so that only one scanner can set the pageblock skip for
exclusive use. Any scanner contending will continue with a linear scan.
The skip bit is still set if no pages can be isolated in a range. While
this may result in redundant scanning, it avoids unnecessarily acquiring
the zone lock when there are no suitable migration sources.
1-socket thpscale
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 3390.40 ( 0.00%) 3024.41 ( 10.80%)
Amean fault-both-5 5082.28 ( 0.00%) 4749.30 ( 6.55%)
Amean fault-both-7 7012.51 ( 0.00%) 6454.95 ( 7.95%)
Amean fault-both-12 11346.63 ( 0.00%) 10324.83 ( 9.01%)
Amean fault-both-18 15324.19 ( 0.00%) 12896.82 * 15.84%*
Amean fault-both-24 16088.50 ( 0.00%) 13470.60 * 16.27%*
Amean fault-both-30 18723.42 ( 0.00%) 17143.99 ( 8.44%)
Amean fault-both-32 18612.01 ( 0.00%) 17743.91 ( 4.66%)
5.0.0-rc1 5.0.0-rc1
findmig-v3r15 isolmig-v3r15
Percentage huge-3 89.83 ( 0.00%) 92.96 ( 3.48%)
Percentage huge-5 91.96 ( 0.00%) 93.26 ( 1.41%)
Percentage huge-7 92.85 ( 0.00%) 93.63 ( 0.84%)
Percentage huge-12 92.74 ( 0.00%) 92.80 ( 0.07%)
Percentage huge-18 91.71 ( 0.00%) 91.62 ( -0.10%)
Percentage huge-24 92.13 ( 0.00%) 91.50 ( -0.69%)
Percentage huge-30 93.79 ( 0.00%) 92.73 ( -1.13%)
Percentage huge-32 91.27 ( 0.00%) 91.94 ( 0.74%)
This shows a reasonable reduction in latency as multiple compaction
scanners do not operate on the same blocks with a similar allocation
success rate.
Compaction migrate scanned 41093126 25646769
Migration scan rates are reduced by 38%.
Link: http://lkml.kernel.org/r/20190118175136.31341-11-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The migration scanner is a linear scan of a zone with a potentiall large
search space. Furthermore, many pageblocks are unusable such as those
filled with reserved pages or partially filled with pages that cannot
migrate. These still get scanned in the common case of allocating a THP
and the cost accumulates.
The patch uses a partial search of the free lists to locate a migration
source candidate that is marked as MOVABLE when allocating a THP. It
prefers picking a block with a larger number of free pages already on
the basis that there are fewer pages to migrate to free the entire
block. The lowest PFN found during searches is tracked as the basis of
the start for the linear search after the first search of the free list
fails. After the search, the free list is shuffled so that the next
search will not encounter the same page. If the search fails then the
subsequent searches will be shorter and the linear scanner is used.
If this search fails, or if the request is for a small or
unmovable/reclaimable allocation then the linear scanner is still used.
It is somewhat pointless to use the list search in those cases. Small
free pages must be used for the search and there is no guarantee that
movable pages are located within that block that are contiguous.
5.0.0-rc1 5.0.0-rc1
noboost-v3r10 findmig-v3r15
Amean fault-both-3 3771.41 ( 0.00%) 3390.40 ( 10.10%)
Amean fault-both-5 5409.05 ( 0.00%) 5082.28 ( 6.04%)
Amean fault-both-7 7040.74 ( 0.00%) 7012.51 ( 0.40%)
Amean fault-both-12 11887.35 ( 0.00%) 11346.63 ( 4.55%)
Amean fault-both-18 16718.19 ( 0.00%) 15324.19 ( 8.34%)
Amean fault-both-24 21157.19 ( 0.00%) 16088.50 * 23.96%*
Amean fault-both-30 21175.92 ( 0.00%) 18723.42 * 11.58%*
Amean fault-both-32 21339.03 ( 0.00%) 18612.01 * 12.78%*
5.0.0-rc1 5.0.0-rc1
noboost-v3r10 findmig-v3r15
Percentage huge-3 86.50 ( 0.00%) 89.83 ( 3.85%)
Percentage huge-5 92.52 ( 0.00%) 91.96 ( -0.61%)
Percentage huge-7 92.44 ( 0.00%) 92.85 ( 0.44%)
Percentage huge-12 92.98 ( 0.00%) 92.74 ( -0.25%)
Percentage huge-18 91.70 ( 0.00%) 91.71 ( 0.02%)
Percentage huge-24 91.59 ( 0.00%) 92.13 ( 0.60%)
Percentage huge-30 90.14 ( 0.00%) 93.79 ( 4.04%)
Percentage huge-32 90.03 ( 0.00%) 91.27 ( 1.37%)
This shows an improvement in allocation latencies with similar
allocation success rates. While not presented, there was a 31%
reduction in migration scanning and a 8% reduction on system CPU usage.
A 2-socket machine showed similar benefits.
[mgorman@techsingularity.net: several fixes]
Link: http://lkml.kernel.org/r/20190204120111.GL9565@techsingularity.net
[vbabka@suse.cz: migrate block that was found-fast, some optimisations]
Link: http://lkml.kernel.org/r/20190118175136.31341-10-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <Vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
compaction
When pageblocks get fragmented, watermarks are artifically boosted to
reclaim pages to avoid further fragmentation events. However,
compaction is often either fragmentation-neutral or moving movable pages
away from unmovable/reclaimable pages. As the true watermarks are
preserved, allow compaction to ignore the boost factor.
The expected impact is very slight as the main benefit is that
compaction is slightly more likely to succeed when the system has been
fragmented very recently. On both 1-socket and 2-socket machines for
THP-intensive allocation during fragmentation the success rate was
increased by less than 1% which is marginal. However, detailed tracing
indicated that failure of migration due to a premature ENOMEM triggered
by watermark checks were eliminated.
Link: http://lkml.kernel.org/r/20190118175136.31341-9-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
When compaction is finishing, it uses a flag to ensure the pageblock is
complete but it makes sense to always complete migration of a pageblock.
Minimally, skip information is based on a pageblock and partially
scanned pageblocks may incur more scanning in the future. The pageblock
skip handling also becomes more strict later in the series and the hint
is more useful if a complete pageblock was always scanned.
The potentially impacts latency as more scanning is done but it's not a
consistent win or loss as the scanning is not always a high percentage
of the pageblock and sometimes it is offset by future reductions in
scanning. Hence, the results are not presented this time due to a
misleading mix of gains/losses without any clear pattern. However, full
scanning of the pageblock is important for later patches.
Link: http://lkml.kernel.org/r/20190118175136.31341-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Pages with no migration handler use a fallback handler which sometimes
works and sometimes persistently retries. A historical example was
blockdev pages but there are others such as odd refcounting when
page->private is used. These are retried multiple times which is
wasteful during compaction so this patch will fail migration faster
unless the caller specifies MIGRATE_SYNC.
This is not expected to help THP allocation success rates but it did
reduce latencies very slightly in some cases.
1-socket thpfioscale
4.20.0 4.20.0
noreserved-v2r15 failfast-v2r15
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 3839.67 ( 0.00%) 3833.72 ( 0.15%)
Amean fault-both-5 5177.47 ( 0.00%) 4967.15 ( 4.06%)
Amean fault-both-7 7245.03 ( 0.00%) 7139.19 ( 1.46%)
Amean fault-both-12 11534.89 ( 0.00%) 11326.30 ( 1.81%)
Amean fault-both-18 16241.10 ( 0.00%) 16270.70 ( -0.18%)
Amean fault-both-24 19075.91 ( 0.00%) 19839.65 ( -4.00%)
Amean fault-both-30 22712.11 ( 0.00%) 21707.05 ( 4.43%)
Amean fault-both-32 21692.92 ( 0.00%) 21968.16 ( -1.27%)
The 2-socket results are not materially different. Scan rates are
similar as expected.
Link: http://lkml.kernel.org/r/20190118175136.31341-7-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
It's non-obvious that high-order free pages are split into order-0 pages
from the function name. Fix it.
Link: http://lkml.kernel.org/r/20190118175136.31341-6-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
A zone parameter is passed into a number of top-level compaction
functions despite the fact that it's already in compact_control. This
is harmless but it did need an audit to check if zone actually ever
changes meaningfully. This patches removes the parameter in a number of
top-level functions. The change could be much deeper but this was
enough to briefly clarify the flow.
No functional change.
Link: http://lkml.kernel.org/r/20190118175136.31341-5-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The last_migrated_pfn field is a bit dubious as to whether it really
helps but either way, the information from it can be inferred without
increasing the size of compact_control so remove the field.
Link: http://lkml.kernel.org/r/20190118175136.31341-4-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
compact_control spans two cache lines with write-intensive lines on
both. Rearrange so the most write-intensive fields are in the same
cache line. This has a negligible impact on the overall performance of
compaction and is more a tidying exercise than anything.
Link: http://lkml.kernel.org/r/20190118175136.31341-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "Increase success rates and reduce latency of compaction", v3.
This series reduces scan rates and success rates of compaction,
primarily by using the free lists to shorten scans, better controlling
of skip information and whether multiple scanners can target the same
block and capturing pageblocks before being stolen by parallel requests.
The series is based on mmotm from January 9th, 2019 with the previous
compaction series reverted.
I'm mostly using thpscale to measure the impact of the series. The
benchmark creates a large file, maps it, faults it, punches holes in the
mapping so that the virtual address space is fragmented and then tries
to allocate THP. It re-executes for different numbers of threads. From
a fragmentation perspective, the workload is relatively benign but it
does stress compaction.
The overall impact on latencies for a 1-socket machine is
baseline patches
Amean fault-both-3 3832.09 ( 0.00%) 2748.56 * 28.28%*
Amean fault-both-5 4933.06 ( 0.00%) 4255.52 ( 13.73%)
Amean fault-both-7 7017.75 ( 0.00%) 6586.93 ( 6.14%)
Amean fault-both-12 11610.51 ( 0.00%) 9162.34 * 21.09%*
Amean fault-both-18 17055.85 ( 0.00%) 11530.06 * 32.40%*
Amean fault-both-24 19306.27 ( 0.00%) 17956.13 ( 6.99%)
Amean fault-both-30 22516.49 ( 0.00%) 15686.47 * 30.33%*
Amean fault-both-32 23442.93 ( 0.00%) 16564.83 * 29.34%*
The allocation success rates are much improved
baseline patches
Percentage huge-3 85.99 ( 0.00%) 97.96 ( 13.92%)
Percentage huge-5 88.27 ( 0.00%) 96.87 ( 9.74%)
Percentage huge-7 85.87 ( 0.00%) 94.53 ( 10.09%)
Percentage huge-12 82.38 ( 0.00%) 98.44 ( 19.49%)
Percentage huge-18 83.29 ( 0.00%) 99.14 ( 19.04%)
Percentage huge-24 81.41 ( 0.00%) 97.35 ( 19.57%)
Percentage huge-30 80.98 ( 0.00%) 98.05 ( 21.08%)
Percentage huge-32 80.53 ( 0.00%) 97.06 ( 20.53%)
That's a nearly perfect allocation success rate.
The biggest impact is on the scan rates
Compaction migrate scanned 55893379 19341254
Compaction free scanned 474739990 11903963
The number of pages scanned for migration was reduced by 65% and the
free scanner was reduced by 97.5%. So much less work in exchange for
lower latency and better success rates.
The series was also evaluated using a workload that heavily fragments
memory but the benefits there are also significant, albeit not
presented.
It was commented that we should be rethinking scanning entirely and to a
large extent I agree. However, to achieve that you need a lot of this
series in place first so it's best to make the linear scanners as best
as possible before ripping them out.
This patch (of 22):
The isolate and migrate scanners should never isolate more than a
pageblock of pages so unsigned int is sufficient saving 8 bytes on a
64-bit build.
Link: http://lkml.kernel.org/r/20190118175136.31341-2-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The 'end_byte' parameter of filemap_range_has_page is required to be
inclusive, so follow the rule.
Link: http://lkml.kernel.org/r/1548678679-18122-1-git-send-email-zhengbin13@huawei.com
Fixes: 6be96d3ad34a ("fs: return if direct I/O will trigger writeback")
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hou Tao <houtao1@huawei.com>
Cc: zhangyi (F) <yi.zhang@huawei.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
swap_vma_readahead()'s comment is missing, just add it.
Link: http://lkml.kernel.org/r/1546543673-108536-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Hugh Dickins <hughd@google.com
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Swap readahead would read in a few pages regardless if the underlying
device is busy or not. It may incur long waiting time if the device is
congested, and it may also exacerbate the congestion.
Use inode_read_congested() to check if the underlying device is busy or
not like what file page readahead does. Get inode from
swap_info_struct.
Although we can add inode information in swap_address_space
(address_space->host), it may lead some unexpected side effect, i.e. it
may break mapping_cap_account_dirty(). Using inode from
swap_info_struct seems simple and good enough.
Just does the check in vma_cluster_readahead() since
swap_vma_readahead() is just used for non-rotational device which much
less likely has congestion than traditional HDD.
Although swap slots may be consecutive on swap partition, it still may
be fragmented on swap file. This check would help to reduce excessive
stall for such case.
The test with page_fault1 of will-it-scale (sometimes tracing may just
show runtest.py that is the wrapper script of page_fault1), which
basically launches NR_CPU threads to generate 128MB anonymous pages for
each thread, on my virtual machine with congested HDD shows long tail
latency is reduced significantly.
Without the patch
page_fault1_thr-1490 [023] 129.311706: funcgraph_entry: #57377.796 us | do_swap_page();
page_fault1_thr-1490 [023] 129.369103: funcgraph_entry: 5.642us | do_swap_page();
page_fault1_thr-1490 [023] 129.369119: funcgraph_entry: #1289.592 us | do_swap_page();
page_fault1_thr-1490 [023] 129.370411: funcgraph_entry: 4.957us | do_swap_page();
page_fault1_thr-1490 [023] 129.370419: funcgraph_entry: 1.940us | do_swap_page();
page_fault1_thr-1490 [023] 129.378847: funcgraph_entry: #1411.385 us | do_swap_page();
page_fault1_thr-1490 [023] 129.380262: funcgraph_entry: 3.916us | do_swap_page();
page_fault1_thr-1490 [023] 129.380275: funcgraph_entry: #4287.751 us | do_swap_page();
With the patch
runtest.py-1417 [020] 301.925911: funcgraph_entry: #9870.146 us | do_swap_page();
runtest.py-1417 [020] 301.935785: funcgraph_entry: 9.802us | do_swap_page();
runtest.py-1417 [020] 301.935799: funcgraph_entry: 3.551us | do_swap_page();
runtest.py-1417 [020] 301.935806: funcgraph_entry: 2.142us | do_swap_page();
runtest.py-1417 [020] 301.935853: funcgraph_entry: 6.938us | do_swap_page();
runtest.py-1417 [020] 301.935864: funcgraph_entry: 3.765us | do_swap_page();
runtest.py-1417 [020] 301.935871: funcgraph_entry: 3.600us | do_swap_page();
runtest.py-1417 [020] 301.935878: funcgraph_entry: 7.202us | do_swap_page();
[akpm@linux-foundation.org: code cleanup]
[yang.shi@linux.alibaba.com: add comment]
Link: http://lkml.kernel.org/r/bbc7bda7-62d0-df1a-23ef-d369e865bdca@linux.alibaba.com
Link: http://lkml.kernel.org/r/1546543673-108536-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Tim Chen <tim.c.chen@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Hugh Dickins <hughd@google.com
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
After we establish a reference on the page, we check the pointer
continues to be in the correct position in i_pages. Checking
page->index afterwards is unnecessary; if it were to change, then the
pointer to it from the page cache would also move. The check used to be
done before grabbing a reference on the page which was racy (see commit
9cbb4cb21b19f ("mm: find_get_pages_contig fixlet")), but nobody noticed
that moving the check after grabbing the reference was redundant.
Link: http://lkml.kernel.org/r/20190107200224.13260-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct foo {
int stuff;
void *entry[];
};
instance = kmalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
This code was detected with the help of Coccinelle.
Link: http://lkml.kernel.org/r/20190104183726.GA6374@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
In the current implementation, there are two places to isolate a range
of page: __offline_pages() and alloc_contig_range(). During this
procedure, it will drain pages on pcp list.
Below is a brief call flow:
__offline_pages()/alloc_contig_range()
start_isolate_page_range()
set_migratetype_isolate()
drain_all_pages()
drain_all_pages() <--- A
This snippet shows the current logic is isolate and drain pcp list for
each pageblock and drain pcp list again for the whole range.
start_isolate_page_range is responsible for isolating the given pfn
range. One part of that job is to make sure that also pages that are on
the allocator pcp lists are properly isolated. Otherwise they could be
reused and the range wouldn't be completely isolated until the memory is
freed back. While there is no strict guarantee here because pages might
get allocated at any time before drain_all_pages is called there doesn't
seem to be any strong demand for such a guarantee.
In any case, draining is already done at the isolation level and there
is no need to do it again later by start_isolate_page_range callers
(memory hotplug and CMA allocator currently). Therefore remove
pointless draining in existing callers to make the code more clear and
functionally correct.
[mhocko@suse.com: provide a clearer changelog for the last two paragraphs]
Link: http://lkml.kernel.org/r/20190105233141.2329-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "arm64/mm: Enable HugeTLB migration", v4.
This patch series enables HugeTLB migration support for all supported
huge page sizes at all levels including contiguous bit implementation.
Following HugeTLB migration support matrix has been enabled with this
patch series. All permutations have been tested except for the 16GB.
CONT PTE PMD CONT PMD PUD
-------- --- -------- ---
4K: 64K 2M 32M 1G
16K: 2M 32M 1G
64K: 2M 512M 16G
First the series adds migration support for PUD based huge pages. It
then adds a platform specific hook to query an architecture if a given
huge page size is supported for migration while also providing a default
fallback option preserving the existing semantics which just checks for
(PMD|PUD|PGDIR)_SHIFT macros. The last two patches enables HugeTLB
migration on arm64 and subscribe to this new platform specific hook by
defining an override.
The second patch differentiates between movability and migratability
aspects of huge pages and implements hugepage_movable_supported() which
can then be used during allocation to decide whether to place the huge
page in movable zone or not.
This patch (of 5):
During huge page allocation it's migratability is checked to determine
if it should be placed under movable zones with GFP_HIGHUSER_MOVABLE.
But the movability aspect of the huge page could depend on other factors
than just migratability. Movability in itself is a distinct property
which should not be tied with migratability alone.
This differentiates these two and implements an enhanced movability check
which also considers huge page size to determine if it is feasible to be
placed under a movable zone. At present it just checks for gigantic pages
but going forward it can incorporate other enhanced checks.
Link: http://lkml.kernel.org/r/1545121450-1663-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
sysctl_extfrag_handler() neglects to propagate the return value from
proc_dointvec_minmax() to its caller. It's a wrapper that doesn't need
to exist, so just use proc_dointvec_minmax() directly.
Link: http://lkml.kernel.org/r/20190104032557.3056-1-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reported-by: Aditya Pakki <pakki001@umn.edu>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Export __vmaloc_node_range() function if CONFIG_TEST_VMALLOC_MODULE is
enabled. Some test cases in vmalloc test suite module require and make
use of that function. Please note, that it is not supposed to be used
for other purposes.
We need it only for performance analysis, stressing and stability check
of vmalloc allocator.
Link: http://lkml.kernel.org/r/20190103142108.20744-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
vmalloc_user*() calls differ from normal vmalloc() only in that they set
VM_USERMAP flags for the area. During the whole history of vmalloc.c
changes now it is possible simply to pass VM_USERMAP flags directly to
__vmalloc_node_range() call instead of finding the area (which obviously
takes time) after the allocation.
Link: http://lkml.kernel.org/r/20190103145954.16942-4-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
__vmalloc_area_node() calls vfree() on error path, which in turn calls
kmemleak_free(), but area is not yet accounted by kmemleak_vmalloc().
Link: http://lkml.kernel.org/r/20190103145954.16942-3-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
When VM_NO_GUARD is not set area->size includes adjacent guard page,
thus for correct size checking get_vm_area_size() should be used, but
not area->size.
This fixes possible kernel oops when userspace tries to mmap an area on
1 page bigger than was allocated by vmalloc_user() call: the size check
inside remap_vmalloc_range_partial() accounts non-existing guard page
also, so check successfully passes but vmalloc_to_page() returns NULL
(guard page does not physically exist).
The following code pattern example should trigger an oops:
static int oops_mmap(struct file *file, struct vm_area_struct *vma)
{
void *mem;
mem = vmalloc_user(4096);
BUG_ON(!mem);
/* Do not care about mem leak */
return remap_vmalloc_range(vma, mem, 0);
}
And userspace simply mmaps size + PAGE_SIZE:
mmap(NULL, 8192, PROT_WRITE|PROT_READ, MAP_PRIVATE, fd, 0);
Possible candidates for oops which do not have any explicit size
checks:
*** drivers/media/usb/stkwebcam/stk-webcam.c:
v4l_stk_mmap[789] ret = remap_vmalloc_range(vma, sbuf->buffer, 0);
Or the following one:
*** drivers/video/fbdev/core/fbmem.c
static int
fb_mmap(struct file *file, struct vm_area_struct * vma)
...
res = fb->fb_mmap(info, vma);
Where fb_mmap callback calls remap_vmalloc_range() directly without any
explicit checks:
*** drivers/video/fbdev/vfb.c
static int vfb_mmap(struct fb_info *info,
struct vm_area_struct *vma)
{
return remap_vmalloc_range(vma, (void *)info->fix.smem_start, vma->vm_pgoff);
}
Link: http://lkml.kernel.org/r/20190103145954.16942-2-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Joe Perches <joe@perches.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This patch repeats the original one from David S Miller:
2dca6999eed5 ("mm, perf_event: Make vmalloc_user() align base kernel virtual address to SHMLBA")
but for missed vmalloc_32_user() case, which also requires correct
alignment of virtual address on kernel side to avoid D-caches aliases.
A bit of copy-paste from original patch to recover in memory of what is
all about:
When a vmalloc'd area is mmap'd into userspace, some kind of
co-ordination is necessary for this to work on platforms with cpu
D-caches which can have aliases.
Otherwise kernel side writes won't be seen properly in userspace and
vice versa.
If the kernel side mapping and the user side one have the same
alignment, modulo SHMLBA, this can work as long as VM_SHARED is shared
of VMA and for all current users this is true. VM_SHARED will force
SHMLBA alignment of the user side mmap on platforms with D-cache
aliasing matters.
David S. Miller
> What are the user-visible runtime effects of this change?
In simple words: proper alignment avoids possible difference in data,
seen by different virtual mapings: userspace and kernel in our case.
I.e. userspace reads cache line A, kernel writes to cache line B. Both
cache lines correspond to the same physical memory (thus aliases).
So this should fix data corruption for archs with vivt and vipt caches,
e.g. armv6. Personally I've never worked with this archs, I just
spotted the strange difference in code: for one case we do alignment,
for another - not. I have a strong feeling that David simply missed
vmalloc_32_user() case.
>
> Is a -stable backport needed?
No, I do not think so. The only one user of vmalloc_32_user() is
virtual frame buffer device drivers/video/fbdev/vfb.c, which has in the
description "The main use of this frame buffer device is testing and
debugging the frame buffer subsystem. Do NOT enable it for normal
systems!".
And it seems to me that this vfb.c does not need 32bit addressable pages
(vmalloc_32_user() case), because it is virtual device and should not
care about things like dma32 zones, etc. Probably is better to clean
the code and switch vfb.c from vmalloc_32_user() to vmalloc_user() case
and wipe out vmalloc_32_user() from vmalloc.c completely. But I'm not
very much sure that this is worth to do, that's so minor, so we can
leave it as is.
Link: http://lkml.kernel.org/r/20190108110944.23591-1-rpenyaev@suse.de
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Move the memcg_kmem_enabled() checks into memcg kmem charge/uncharge
functions, so, the users don't have to explicitly check that condition.
This is purely code cleanup patch without any functional change. Only
the order of checks in memcg_charge_slab() can potentially be changed
but the functionally it will be same. This should not matter as
memcg_charge_slab() is not in the hot path.
Link: http://lkml.kernel.org/r/20190103161203.162375-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
There are two cases when put_cpu_partial() is invoked.
* __slab_free
* get_partial_node
This patch just makes it cover these two cases.
Link: http://lkml.kernel.org/r/20181025094437.18951-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
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>
|
|
Add an optimization for KSM pages almost in the same way that we have
for ordinary anonymous pages. If there is a write fault in a page,
which is mapped to an only pte, and it is not related to swap cache; the
page may be reused without copying its content.
[ Note that we do not consider PageSwapCache() pages at least for now,
since we don't want to complicate __get_ksm_page(), which has nice
optimization based on this (for the migration case). Currenly it is
spinning on PageSwapCache() pages, waiting for when they have
unfreezed counters (i.e., for the migration finish). But we don't want
to make it also spinning on swap cache pages, which we try to reuse,
since there is not a very high probability to reuse them. So, for now
we do not consider PageSwapCache() pages at all. ]
So in reuse_ksm_page() we check for 1) PageSwapCache() and 2)
page_stable_node(), to skip a page, which KSM is currently trying to
link to stable tree. Then we do page_ref_freeze() to prohibit KSM to
merge one more page into the page, we are reusing. After that, nobody
can refer to the reusing page: KSM skips !PageSwapCache() pages with
zero refcount; and the protection against of all other participants is
the same as for reused ordinary anon pages pte lock, page lock and
mmap_sem.
[akpm@linux-foundation.org: replace BUG_ON()s with WARN_ON()s]
Link: http://lkml.kernel.org/r/154471491016.31352.1168978849911555609.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "Replace all open encodings for NUMA_NO_NODE", v3.
All these places for replacement were found by running the following
grep patterns on the entire kernel code. Please let me know if this
might have missed some instances. This might also have replaced some
false positives. I will appreciate suggestions, inputs and review.
1. git grep "nid == -1"
2. git grep "node == -1"
3. git grep "nid = -1"
4. git grep "node = -1"
This patch (of 2):
At present there are multiple places where invalid node number is
encoded as -1. Even though implicitly understood it is always better to
have macros in there. Replace these open encodings for an invalid node
number with the global macro NUMA_NO_NODE. This helps remove NUMA
related assumptions like 'invalid node' from various places redirecting
them to a common definition.
Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe]
Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx]
Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c]
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband]
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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find_vmap_area() can return a NULL pointer and we're going to
dereference it without checking it first. Use the existing
find_vm_area() function which does exactly what we want and checks for
the NULL pointer.
Link: http://lkml.kernel.org/r/20181228171009.22269-1-liviu@dudau.co.uk
Fixes: f3c01d2f3ade ("mm: vmalloc: avoid racy handling of debugobjects in vunmap")
Signed-off-by: Liviu Dudau <liviu@dudau.co.uk>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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