mm/compaction: fix bug in hugetlb handling pathway

The compaction code doesn't take references on pages until we're certain
we should attempt to handle it.

In the hugetlb case, isolate_or_dissolve_

mm/compaction: fix bug in hugetlb handling pathway

The compaction code doesn't take references on pages until we're certain
we should attempt to handle it.

In the hugetlb case, isolate_or_dissolve_huge_page() may return -EBUSY
without taking a reference to the folio associated with our pfn. If our
folio's refcount drops to 0, compound_nr() becomes unpredictable, making
low_pfn and nr_scanned unreliable. The user-visible effect is minimal -
this should rarely happen (if ever).

Fix this by storing the folio statistics earlier on the stack (just like
the THP and Buddy cases).

Also revert commit 66fe1cf7f581 ("mm: compaction: use helper compound_nr
in isolate_migratepages_block") to make backporting easier.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 369fa227c219 ("mm: make alloc_contig_range handle free hugetlb pages")
Signed-off-by: Vishal Moola (Oracle) <[email protected]>
Acked-by: Oscar Salvador <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: page_alloc: defrag_mode kswapd/kcompactd watermarks

The previous patch added pageblock_order reclaim to kswapd/kcompactd,
which helps, but produces only one block at a time. Allocation stalls a

mm: page_alloc: defrag_mode kswapd/kcompactd watermarks

The previous patch added pageblock_order reclaim to kswapd/kcompactd,
which helps, but produces only one block at a time. Allocation stalls and
THP failure rates are still higher than they could be.

To adequately reflect ALLOC_NOFRAGMENT demand for pageblocks, change the
watermarking for kswapd & kcompactd: instead of targeting the high
watermark in order-0 pages and checking for one suitable block, simply
require that the high watermark is entirely met in pageblocks.

To this end, track the number of free pages within contiguous pageblocks,
then change pgdat_balanced() and compact_finished() to check watermarks
against this new value.

This further reduces THP latencies and allocation stalls, and improves THP
success rates against the previous patch:

DEFRAGMODE-ASYNC DEFRAGMODE-ASYNC-WMARKS
Hugealloc Time mean 34300.36 ( +0.00%) 28904.00 ( -15.73%)
Hugealloc Time stddev 36390.42 ( +0.00%) 33464.37 ( -8.04%)
Kbuild Real time 196.13 ( +0.00%) 196.59 ( +0.23%)
Kbuild User time 1234.74 ( +0.00%) 1231.67 ( -0.25%)
Kbuild System time 62.62 ( +0.00%) 59.10 ( -5.54%)
THP fault alloc 57054.53 ( +0.00%) 63223.67 ( +10.81%)
THP fault fallback 11581.40 ( +0.00%) 5412.47 ( -53.26%)
Direct compact fail 107.80 ( +0.00%) 59.07 ( -44.79%)
Direct compact success 4.53 ( +0.00%) 2.80 ( -31.33%)
Direct compact success rate % 3.20 ( +0.00%) 3.99 ( +18.66%)
Compact daemon scanned migrate 5461033.93 ( +0.00%) 2267500.33 ( -58.48%)
Compact daemon scanned free 5824897.93 ( +0.00%) 2339773.00 ( -59.83%)
Compact direct scanned migrate 58336.93 ( +0.00%) 47659.93 ( -18.30%)
Compact direct scanned free 32791.87 ( +0.00%) 40729.67 ( +24.21%)
Compact total migrate scanned 5519370.87 ( +0.00%) 2315160.27 ( -58.05%)
Compact total free scanned 5857689.80 ( +0.00%) 2380502.67 ( -59.36%)
Alloc stall 2424.60 ( +0.00%) 638.87 ( -73.62%)
Pages kswapd scanned 2657018.33 ( +0.00%) 4002186.33 ( +50.63%)
Pages kswapd reclaimed 559583.07 ( +0.00%) 718577.80 ( +28.41%)
Pages direct scanned 722094.07 ( +0.00%) 355172.73 ( -50.81%)
Pages direct reclaimed 107257.80 ( +0.00%) 31162.80 ( -70.95%)
Pages total scanned 3379112.40 ( +0.00%) 4357359.07 ( +28.95%)
Pages total reclaimed 666840.87 ( +0.00%) 749740.60 ( +12.43%)
Swap out 77238.20 ( +0.00%) 110084.33 ( +42.53%)
Swap in 11712.80 ( +0.00%) 24457.00 ( +108.80%)
File refaults 143438.80 ( +0.00%) 188226.93 ( +31.22%)

Also of note is that compaction work overall is reduced. The reason for
this is that when free pageblocks are more readily available, allocations
are also much more likely to get physically placed in LRU order, instead
of being forced to scavenge free space here and there. This means that
reclaim by itself has better chances of freeing up whole blocks, and the
system relies less on compaction.

Comparing all changes to the vanilla kernel:

VANILLA DEFRAGMODE-ASYNC-WMARKS
Hugealloc Time mean 52739.45 ( +0.00%) 28904.00 ( -45.19%)
Hugealloc Time stddev 56541.26 ( +0.00%) 33464.37 ( -40.81%)
Kbuild Real time 197.47 ( +0.00%) 196.59 ( -0.44%)
Kbuild User time 1240.49 ( +0.00%) 1231.67 ( -0.71%)
Kbuild System time 70.08 ( +0.00%) 59.10 ( -15.45%)
THP fault alloc 46727.07 ( +0.00%) 63223.67 ( +35.30%)
THP fault fallback 21910.60 ( +0.00%) 5412.47 ( -75.29%)
Direct compact fail 195.80 ( +0.00%) 59.07 ( -69.48%)
Direct compact success 7.93 ( +0.00%) 2.80 ( -57.46%)
Direct compact success rate % 3.51 ( +0.00%) 3.99 ( +10.49%)
Compact daemon scanned migrate 3369601.27 ( +0.00%) 2267500.33 ( -32.71%)
Compact daemon scanned free 5075474.47 ( +0.00%) 2339773.00 ( -53.90%)
Compact direct scanned migrate 161787.27 ( +0.00%) 47659.93 ( -70.54%)
Compact direct scanned free 163467.53 ( +0.00%) 40729.67 ( -75.08%)
Compact total migrate scanned 3531388.53 ( +0.00%) 2315160.27 ( -34.44%)
Compact total free scanned 5238942.00 ( +0.00%) 2380502.67 ( -54.56%)
Alloc stall 2371.07 ( +0.00%) 638.87 ( -73.02%)
Pages kswapd scanned 2160926.73 ( +0.00%) 4002186.33 ( +85.21%)
Pages kswapd reclaimed 533191.07 ( +0.00%) 718577.80 ( +34.77%)
Pages direct scanned 400450.33 ( +0.00%) 355172.73 ( -11.31%)
Pages direct reclaimed 94441.73 ( +0.00%) 31162.80 ( -67.00%)
Pages total scanned 2561377.07 ( +0.00%) 4357359.07 ( +70.12%)
Pages total reclaimed 627632.80 ( +0.00%) 749740.60 ( +19.46%)
Swap out 47959.53 ( +0.00%) 110084.33 ( +129.53%)
Swap in 7276.00 ( +0.00%) 24457.00 ( +236.10%)
File refaults 138043.00 ( +0.00%) 188226.93 ( +36.35%)

THP allocation latencies and %sys time are down dramatically.

THP allocation failures are down from nearly 50% to 8.5%. And to recall
previous data points, the success rates are steady and reliable without
the cumulative deterioration of fragmentation events.

Compaction work is down overall. Direct compaction work especially is
drastically reduced. As an aside, its success rate of 4% indicates there
is room for improvement. For now it's good to rely on it less.

Reclaim work is up overall, however direct reclaim work is down. Part of
the increase can be attributed to a higher use of THPs, which due to
internal fragmentation increase the memory footprint. This is not
necessarily an unexpected side-effect for users of THP.

However, taken both points together, there may well be some opportunities
for fine tuning in the reclaim/compaction coordination.

[[email protected]: fix squawks from rebasing]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Johannes Weiner <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: push watermark into compaction_suitable() callers

Patch series "mm: reliable huge page allocator".

This series makes changes to the allocator and reclaim/compaction code to
try hard

mm: compaction: push watermark into compaction_suitable() callers

Patch series "mm: reliable huge page allocator".

This series makes changes to the allocator and reclaim/compaction code to
try harder to avoid fragmentation. As a result, this makes huge page
allocations cheaper, more reliable and more sustainable.

It's a subset of the huge page allocator RFC initially proposed here:

https://lore.kernel.org/lkml/[email protected]/

The following results are from a kernel build test, with additional
concurrent bursts of THP allocations on a memory-constrained system.
Comparing before and after the changes over 15 runs:

before after
Hugealloc Time mean 52739.45 ( +0.00%) 28904.00 ( -45.19%)
Hugealloc Time stddev 56541.26 ( +0.00%) 33464.37 ( -40.81%)
Kbuild Real time 197.47 ( +0.00%) 196.59 ( -0.44%)
Kbuild User time 1240.49 ( +0.00%) 1231.67 ( -0.71%)
Kbuild System time 70.08 ( +0.00%) 59.10 ( -15.45%)
THP fault alloc 46727.07 ( +0.00%) 63223.67 ( +35.30%)
THP fault fallback 21910.60 ( +0.00%) 5412.47 ( -75.29%)
Direct compact fail 195.80 ( +0.00%) 59.07 ( -69.48%)
Direct compact success 7.93 ( +0.00%) 2.80 ( -57.46%)
Direct compact success rate % 3.51 ( +0.00%) 3.99 ( +10.49%)
Compact daemon scanned migrate 3369601.27 ( +0.00%) 2267500.33 ( -32.71%)
Compact daemon scanned free 5075474.47 ( +0.00%) 2339773.00 ( -53.90%)
Compact direct scanned migrate 161787.27 ( +0.00%) 47659.93 ( -70.54%)
Compact direct scanned free 163467.53 ( +0.00%) 40729.67 ( -75.08%)
Compact total migrate scanned 3531388.53 ( +0.00%) 2315160.27 ( -34.44%)
Compact total free scanned 5238942.00 ( +0.00%) 2380502.67 ( -54.56%)
Alloc stall 2371.07 ( +0.00%) 638.87 ( -73.02%)
Pages kswapd scanned 2160926.73 ( +0.00%) 4002186.33 ( +85.21%)
Pages kswapd reclaimed 533191.07 ( +0.00%) 718577.80 ( +34.77%)
Pages direct scanned 400450.33 ( +0.00%) 355172.73 ( -11.31%)
Pages direct reclaimed 94441.73 ( +0.00%) 31162.80 ( -67.00%)
Pages total scanned 2561377.07 ( +0.00%) 4357359.07 ( +70.12%)
Pages total reclaimed 627632.80 ( +0.00%) 749740.60 ( +19.46%)
Swap out 47959.53 ( +0.00%) 110084.33 ( +129.53%)
Swap in 7276.00 ( +0.00%) 24457.00 ( +236.10%)
File refaults 138043.00 ( +0.00%) 188226.93 ( +36.35%)

THP latencies are cut in half, and failure rates are cut by 75%. These
metrics also hold up over time, while the vanilla kernel sees a steady
downward trend in success rates with each subsequent run, owed to the
cumulative effects of fragmentation.

A more detailed discussion of results is in the patch changelogs.

The patches first introduce a vm.defrag_mode sysctl, which enforces the
existing ALLOC_NOFRAGMENT alloc flag until after reclaim and compaction
have run. They then change kswapd and kcompactd to target pageblocks,
which boosts success in the ALLOC_NOFRAGMENT hotpaths.

Patches #1 and #2 are somewhat unrelated cleanups, but touch the same code
and so are included here to avoid conflicts from re-ordering.


This patch (of 5):

compaction_suitable() hardcodes the min watermark, with a boost to the low
watermark for costly orders. However, compaction_ready() requires order-0
at the high watermark. It currently checks the marks twice.

Make the watermark a parameter to compaction_suitable() and have the
callers pass in what they require:

- compaction_zonelist_suitable() is used by the direct reclaim path,
so use the min watermark.

- compact_suit_allocation_order() has a watermark in context derived
from cc->alloc_flags.

The only quirk is that kcompactd doesn't initialize cc->alloc_flags
explicitly. There is a direct check in kcompactd_do_work() that
passes ALLOC_WMARK_MIN, but there is another check downstack in
compact_zone() that ends up passing the unset alloc_flags. Since
they default to 0, and that coincides with ALLOC_WMARK_MIN, it is
correct. But it's subtle. Set cc->alloc_flags explicitly.

- should_continue_reclaim() is direct reclaim, use the min watermark.

- Finally, consolidate the two checks in compaction_ready() to a
single compaction_suitable() call passing the high watermark.

There is a tiny change in behavior: before, compaction_suitable()
would check order-0 against min or low, depending on costly
order. Then there'd be another high watermark check.

Now, the high watermark is passed to compaction_suitable(), and the
costly order-boost (low - min) is added on top. This means
compaction_ready() sets a marginally higher target for free pages.

In a kernelbuild + THP pressure test, though, this didn't show any
measurable negative effects on memory pressure or reclaim rates. As
the comment above the check says, reclaim is usually stopped short
on should_continue_reclaim(), and this just defines the worst-case
reclaim cutoff in case compaction is not making any headway.

[[email protected]: stop oops on out-of-range highest_zoneidx]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Johannes Weiner <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Zi Yan <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/page_alloc: clarify terminology in migratetype fallback code

Patch series "mm/page_alloc: Some clarifications for migratetype
fallback", v4.

A couple of patches to try and make the code easier t

mm/page_alloc: clarify terminology in migratetype fallback code

Patch series "mm/page_alloc: Some clarifications for migratetype
fallback", v4.

A couple of patches to try and make the code easier to follow.


This patch (of 2):

This code is rather confusing because:

1. "Steal" is sometimes used to refer to the general concept of
allocating from a from a block of a fallback migratetype
(steal_suitable_fallback()) but sometimes it refers specifically to
converting a whole block's migratetype (can_steal_fallback()).

2. can_steal_fallback() sounds as though it's answering the question "am
I functionally permitted to allocate from that other type" but in
fact it is encoding a heuristic preference.

3. The same piece of data has different names in different places:
can_steal vs whole_block. This reinforces point 2 because it looks
like the different names reflect a shift in intent from "am I
allowed to steal" to "do I want to steal", but no such shift exists.

Fix 1. by avoiding the term "steal" in ambiguous contexts. Start using
the term "claim" to refer to the special case of stealing the entire
block.

Fix 2. by using "should" instead of "can", and also rename its
parameters and add some commentary to make it more explicit what they
mean.

Fix 3. by adopting the new "claim" terminology universally for this
set of variables.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Brendan Jackman <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback

Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so
nfs_release_folio() can skip calling nfs_wb_folio() fr

NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback

Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so
nfs_release_folio() can skip calling nfs_wb_folio() from kcompactd.

Otherwise NFS can deadlock waiting for kcompactd enduced writeback which
recurses back to NFS (which triggers writeback to NFSD via NFS loopback
mount on the same host, NFSD blocks waiting for XFS's call to
__filemap_get_folio):

6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds.

{---
[58] "kcompactd0"
[<0>] folio_wait_bit+0xe8/0x200
[<0>] folio_wait_writeback+0x2b/0x80
[<0>] nfs_wb_folio+0x80/0x1b0 [nfs]
[<0>] nfs_release_folio+0x68/0x130 [nfs]
[<0>] split_huge_page_to_list_to_order+0x362/0x840
[<0>] migrate_pages_batch+0x43d/0xb90
[<0>] migrate_pages_sync+0x9a/0x240
[<0>] migrate_pages+0x93c/0x9f0
[<0>] compact_zone+0x8e2/0x1030
[<0>] compact_node+0xdb/0x120
[<0>] kcompactd+0x121/0x2e0
[<0>] kthread+0xcf/0x100
[<0>] ret_from_fork+0x31/0x40
[<0>] ret_from_fork_asm+0x1a/0x30
---}

[[email protected]: fix build]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page")
Signed-off-by: Mike Snitzer <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: use the proper flag to determine watermarks

There are 4 NUMA nodes on my machine, and each NUMA node has 32GB of
memory. I have configured 16GB of CMA memory on each NUMA node, and

mm: compaction: use the proper flag to determine watermarks

There are 4 NUMA nodes on my machine, and each NUMA node has 32GB of
memory. I have configured 16GB of CMA memory on each NUMA node, and
starting a 32GB virtual machine with device passthrough is extremely slow,
taking almost an hour.

Long term GUP cannot allocate memory from CMA area, so a maximum of 16 GB
of no-CMA memory on a NUMA node can be used as virtual machine memory.
There is 16GB of free CMA memory on a NUMA node, which is sufficient to
pass the order-0 watermark check, causing the __compaction_suitable()
function to consistently return true.

For costly allocations, if the __compaction_suitable() function always
returns true, it causes the __alloc_pages_slowpath() function to fail to
exit at the appropriate point. This prevents timely fallback to
allocating memory on other nodes, ultimately resulting in excessively long
virtual machine startup times.

Call trace:
__alloc_pages_slowpath
if (compact_result == COMPACT_SKIPPED ||
compact_result == COMPACT_DEFERRED)
goto nopage; // should exit __alloc_pages_slowpath() from here

We could use the real unmovable allocation context to have
__zone_watermark_unusable_free() subtract CMA pages, and thus we won't
pass the order-0 check anymore once the non-CMA part is exhausted. There
is some risk that in some different scenario the compaction could in fact
migrate pages from the exhausted non-CMA part of the zone to the CMA part
and succeed, and we'll skip it instead. But only __GFP_NORETRY
allocations should be affected in the immediate "goto nopage" when
compaction is skipped, others will attempt with DEF_COMPACT_PRIORITY
anyway and won't fail without trying to compact-migrate the non-CMA
pageblocks into CMA pageblocks first, so it should be fine.

After this fix, it only takes a few tens of seconds to start a 32GB
virtual machine with device passthrough functionality.

Link: https://lore.kernel.org/lkml/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: yangge <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Barry Song <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

treewide: const qualify ctl_tables where applicable

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysc

treewide: const qualify ctl_tables where applicable

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
virtual patch

@
depends on !(file in "net")
disable optional_qualifier
@

identifier table_name != {
watchdog_hardlockup_sysctl,
iwcm_ctl_table,
ucma_ctl_table,
memory_allocation_profiling_sysctls,
loadpin_sysctl_table
};
@@

+ const
struct ctl_table table_name [] = { ... };

sed:
sed --in-place \
-e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
kernel/utsname_sysctl.c

Reviewed-by: Song Liu <[email protected]>
Acked-by: Steven Rostedt (Google) <[email protected]> # for kernel/trace/
Reviewed-by: Martin K. Petersen <[email protected]> # SCSI
Reviewed-by: Darrick J. Wong <[email protected]> # xfs
Acked-by: Jani Nikula <[email protected]>
Acked-by: Corey Minyard <[email protected]>
Acked-by: Wei Liu <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Reviewed-by: Bill O'Donnell <[email protected]>
Acked-by: Baoquan He <[email protected]>
Acked-by: Ashutosh Dixit <[email protected]>
Acked-by: Anna Schumaker <[email protected]>
Signed-off-by: Joel Granados <[email protected]>

show more ...

mm/compaction: fix UBSAN shift-out-of-bounds warning

syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order)
in isolate_freepages_block(). The bogus compound_order can be any value

mm/compaction: fix UBSAN shift-out-of-bounds warning

syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order)
in isolate_freepages_block(). The bogus compound_order can be any value
because it is union with flags. Add back the MAX_PAGE_ORDER check to fix
the warning.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 3da0272a4c7d ("mm/compaction: correctly return failure with bogus compound_order in strict mode")
Signed-off-by: Liu Shixin <[email protected]>
Reviewed-by: Kemeng Shi <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Nanyong Sun <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/page_alloc: move set_page_refcounted() to callers of post_alloc_hook()

In preparation for allocating frozen pages, stop initialising the page
refcount in post_alloc_hook().

Link: https://lkml.ke

mm/page_alloc: move set_page_refcounted() to callers of post_alloc_hook()

In preparation for allocating frozen pages, stop initialising the page
refcount in post_alloc_hook().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: William Kucharski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: Create/affine kcompactd to its preferred node

Kcompactd is dedicated to a specific node. As such it wants to be
preferrably affine to it, memory and CPUs-wise.

Use the proper kthread API to ach

mm: Create/affine kcompactd to its preferred node

Kcompactd is dedicated to a specific node. As such it wants to be
preferrably affine to it, memory and CPUs-wise.

Use the proper kthread API to achieve that. As a bonus it takes care of
CPU-hotplug events and CPU-isolation on its behalf.

Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

show more ...

mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath()

should_reclaim_retry() is not ALLOC_CPUSET aware and that means that it
considers reclaimability of NUMA nodes which are outside

mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath()

should_reclaim_retry() is not ALLOC_CPUSET aware and that means that it
considers reclaimability of NUMA nodes which are outside of the cpuset.
If other nodes have a lot of reclaimable memory then should_reclaim_retry
would instruct page allocator to retry even though there is no memory
reclaimable on the cpuset nodemask. This is not really a huge problem
because the number of retries without any reclaim progress is bound but it
could be certainly improved. This is a cold path so this shouldn't really
have a measurable impact on performance on most workloads.

1.Test step and the machines.
------------
root@vm:/sys/fs/cgroup/test# numactl -H | grep size
node 0 size: 9477 MB
node 1 size: 10079 MB
node 2 size: 10079 MB
node 3 size: 10078 MB

root@vm:/sys/fs/cgroup/test# cat cpuset.mems
2

root@vm:/sys/fs/cgroup/test# stress --vm 1 --vm-bytes 12g --vm-keep
stress: info: [33430] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd
stress: FAIL: [33430] (425) <-- worker 33431 got signal 9
stress: WARN: [33430] (427) now reaping child worker processes
stress: FAIL: [33430] (461) failed run completed in 2s

2. reclaim_retry_zone info:

We can only alloc pages from node=2, but the reclaim_retry_zone is
node=0 and return true.

root@vm:/sys/kernel/debug/tracing# cat trace
stress-33431 [001] ..... 13223.617311: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=1 wmark_check=1
stress-33431 [001] ..... 13223.617682: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=2 wmark_check=1
stress-33431 [001] ..... 13223.618103: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=3 wmark_check=1
stress-33431 [001] ..... 13223.618454: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=4 wmark_check=1
stress-33431 [001] ..... 13223.618770: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=5 wmark_check=1
stress-33431 [001] ..... 13223.619150: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=6 wmark_check=1
stress-33431 [001] ..... 13223.619510: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=7 wmark_check=1
stress-33431 [001] ..... 13223.619850: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=8 wmark_check=1
stress-33431 [001] ..... 13223.620171: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=9 wmark_check=1
stress-33431 [001] ..... 13223.620533: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=10 wmark_check=1
stress-33431 [001] ..... 13223.620894: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=11 wmark_check=1
stress-33431 [001] ..... 13223.621224: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=12 wmark_check=1
stress-33431 [001] ..... 13223.621551: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=13 wmark_check=1
stress-33431 [001] ..... 13223.621847: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=14 wmark_check=1
stress-33431 [001] ..... 13223.622200: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=15 wmark_check=1
stress-33431 [001] ..... 13223.622580: reclaim_retry_zone: node=0 zone=Normal order=0 reclaimable=4260 available=1772019 min_wmark=5962 no_progress_loops=16 wmark_check=1

With this patch, we can check the right node and get less retry in
__alloc_pages_slowpath() because there is nothing to do.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zhongkun He <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Zefan Li <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/contig_alloc: support __GFP_COMP

Patch series "mm/hugetlb: alloc/free gigantic folios", v2.

Use __GFP_COMP for gigantic folios can greatly reduce not only the amount
of code but also the allocat

mm/contig_alloc: support __GFP_COMP

Patch series "mm/hugetlb: alloc/free gigantic folios", v2.

Use __GFP_COMP for gigantic folios can greatly reduce not only the amount
of code but also the allocation and free time.

Approximate LOC to mm/hugetlb.c: +60, -240

Allocate and free 500 1GB hugeTLB memory without HVO by:
time echo 500 >/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
time echo 0 >/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages

Before After
Alloc ~13s ~10s
Free ~15s <1s

The above magnitude generally holds for multiple x86 and arm64 CPU
models.

Perf profile before:
Alloc
- 99.99% alloc_pool_huge_folio
- __alloc_fresh_hugetlb_folio
- 83.23% alloc_contig_pages_noprof
- 47.46% alloc_contig_range_noprof
- 20.96% isolate_freepages_range
16.10% split_page
- 14.10% start_isolate_page_range
- 12.02% undo_isolate_page_range

Free
- update_and_free_pages_bulk
- 87.71% free_contig_range
- 76.02% free_unref_page
- 41.30% free_unref_page_commit
- 32.58% free_pcppages_bulk
- 24.75% __free_one_page
13.96% _raw_spin_trylock
12.27% __update_and_free_hugetlb_folio

Perf profile after:
Alloc
- 99.99% alloc_pool_huge_folio
alloc_gigantic_folio
- alloc_contig_pages_noprof
- 59.15% alloc_contig_range_noprof
- 20.72% start_isolate_page_range
20.64% prep_new_page
- 17.13% undo_isolate_page_range

Free
- update_and_free_pages_bulk
- __folio_put
- __free_pages_ok
7.46% free_tail_page_prepare
- 1.97% free_one_page
1.86% __free_one_page

This patch (of 3):

Support __GFP_COMP in alloc_contig_range(). When the flag is set, upon
success the function returns a large folio prepared by prep_new_page(),
rather than a range of order-0 pages prepared by split_free_pages() (which
is renamed from split_map_pages()).

alloc_contig_range() can be used to allocate folios larger than
MAX_PAGE_ORDER, e.g., gigantic hugeTLB folios. So on the free path,
free_one_page() needs to handle that by split_large_buddy().

[[email protected]: fix folio_alloc_gigantic_noprof() WARN expression, per Yu Liao]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yu Zhao <[email protected]>
Acked-by: Zi Yan <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Frank van der Linden <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

sysctl: treewide: constify the ctl_table argument of proc_handlers

const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ct

sysctl: treewide: constify the ctl_table argument of proc_handlers

const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
virtual patch

@r1@
identifier ctl, write, buffer, lenp, ppos;
identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
@@

int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos);

@r2@
identifier func, ctl, write, buffer, lenp, ppos;
@@

int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int write, void *buffer, size_t *lenp, loff_t *ppos)
{ ... }

@r3@
identifier func;
@@

int func(
- struct ctl_table *
+ const struct ctl_table *
,int , void *, size_t *, loff_t *);

@r4@
identifier func, ctl;
@@

int func(
- struct ctl_table *ctl
+ const struct ctl_table *ctl
,int , void *, size_t *, loff_t *);

@r5@
identifier func, write, buffer, lenp, ppos;
@@

int func(
- struct ctl_table *
+ const struct ctl_table *
,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
conventions. The xfs_stats_clear_proc_handler,
xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
This is called from a proc_handler itself and is calling back into
another proc_handler, making it necessary to change it as part of the
proc_handler migration.

Co-developed-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
Co-developed-by: Joel Granados <[email protected]>
Signed-off-by: Joel Granados <[email protected]>

show more ...

mm, virt: merge AS_UNMOVABLE and AS_INACCESSIBLE

The flags AS_UNMOVABLE and AS_INACCESSIBLE were both added just for guest_memfd;
AS_UNMOVABLE is already in existing versions of Linux, while AS_INAC

mm, virt: merge AS_UNMOVABLE and AS_INACCESSIBLE

The flags AS_UNMOVABLE and AS_INACCESSIBLE were both added just for guest_memfd;
AS_UNMOVABLE is already in existing versions of Linux, while AS_INACCESSIBLE was
acked for inclusion in 6.11.

But really, they are the same thing: only guest_memfd uses them, at least for
now, and guest_memfd pages are unmovable because they should not be
accessed by the CPU.

So merge them into one; use the AS_INACCESSIBLE name which is more comprehensive.
At the same time, this fixes an embarrassing bug where AS_INACCESSIBLE was used
as a bit mask, despite it being just a bit index.

The bug was mostly benign, because AS_INACCESSIBLE's bit representation (1010)
corresponded to setting AS_UNEVICTABLE (which is already set) and AS_ENOSPC
(except no async writes can happen on the guest_memfd). So the AS_INACCESSIBLE
flag simply had no effect.

Fixes: 1d23040caa8b ("KVM: guest_memfd: Use AS_INACCESSIBLE when creating guest_memfd inode")
Fixes: c72ceafbd12c ("mm: Introduce AS_INACCESSIBLE for encrypted/confidential memory")
Cc: [email protected]
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Tested-by: Michael Roth <[email protected]>
Reviewed-by: Michael Roth <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

show more ...

mm: handle profiling for fake memory allocations during compaction

During compaction isolated free pages are marked allocated so that they
can be split and/or freed. For that, post_alloc_hook() is

mm: handle profiling for fake memory allocations during compaction

During compaction isolated free pages are marked allocated so that they
can be split and/or freed. For that, post_alloc_hook() is used inside
split_map_pages() and release_free_list(). split_map_pages() marks free
pages allocated, splits the pages and then lets
alloc_contig_range_noprof() free those pages. release_free_list() marks
free pages and immediately frees them. This usage of post_alloc_hook()
affect memory allocation profiling because these functions might not be
called from an instrumented allocator, therefore current->alloc_tag is
NULL and when debugging is enabled (CONFIG_MEM_ALLOC_PROFILING_DEBUG=y)
that causes warnings. To avoid that, wrap such post_alloc_hook() calls
into an instrumented function which acts as an allocator which will be
charged for these fake allocations. Note that these allocations are very
short lived until they are freed, therefore the associated counters should
usually read 0.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Sourav Panda <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

memory: remove the now superfluous sentinel element from ctl_table array

This commit comes at the tail end of a greater effort to remove the empty
elements at the end of the ctl_table arrays (sentin

memory: remove the now superfluous sentinel element from ctl_table array

This commit comes at the tail end of a greater effort to remove the empty
elements at the end of the ctl_table arrays (sentinels) which will reduce
the overall build time size of the kernel and run time memory bloat by ~64
bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%[email protected]/)

Remove sentinel from all files under mm/ that register a sysctl table.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Joel Granados <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: enable page allocation tagging

Redefine page allocators to record allocation tags upon their invocation.
Instrument post_alloc_hook and free_pages_prepare to modify current
allocation tag.

[su

mm: enable page allocation tagging

Redefine page allocators to record allocation tags upon their invocation.
Instrument post_alloc_hook and free_pages_prepare to modify current
allocation tag.

[[email protected]: undo _noprof additions in the documentation]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Co-developed-by: Kent Overstreet <[email protected]>
Signed-off-by: Kent Overstreet <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations

Sven reports an infinite loop in __alloc_pages_slowpath() for costly order
__GFP_RETRY_MAYFAIL allocations tha

mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations

Sven reports an infinite loop in __alloc_pages_slowpath() for costly order
__GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination
can happen in a suspend/resume context where a GFP_KERNEL allocation can
have __GFP_IO masked out via gfp_allowed_mask.

Quoting Sven:

1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER)
with __GFP_RETRY_MAYFAIL set.

2. page alloc's __alloc_pages_slowpath tries to get a page from the
freelist. This fails because there is nothing free of that costly
order.

3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim,
which bails out because a zone is ready to be compacted; it pretends
to have made a single page of progress.

4. page alloc tries to compact, but this always bails out early because
__GFP_IO is not set (it's not passed by the snd allocator, and even
if it were, we are suspending so the __GFP_IO flag would be cleared
anyway).

5. page alloc believes reclaim progress was made (because of the
pretense in item 3) and so it checks whether it should retry
compaction. The compaction retry logic thinks it should try again,
because:
a) reclaim is needed because of the early bail-out in item 4
b) a zonelist is suitable for compaction

6. goto 2. indefinite stall.

(end quote)

The immediate root cause is confusing the COMPACT_SKIPPED returned from
__alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be
indicating a lack of order-0 pages, and in step 5 evaluating that in
should_compact_retry() as a reason to retry, before incrementing and
limiting the number of retries. There are however other places that
wrongly assume that compaction can happen while we lack __GFP_IO.

To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO
evaluation and switch the open-coded test in try_to_compact_pages() to use
it.

Also use the new helper in:
- compaction_ready(), which will make reclaim not bail out in step 3, so
there's at least one attempt to actually reclaim, even if chances are
small for a costly order
- in_reclaim_compaction() which will make should_continue_reclaim()
return false and we don't over-reclaim unnecessarily
- in __alloc_pages_slowpath() to set a local variable can_compact,
which is then used to avoid retrying reclaim/compaction for costly
allocations (step 5) if we can't compact and also to skip the early
compaction attempt that we do in some cases

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"")
Signed-off-by: Vlastimil Babka <[email protected]>
Reported-by: Sven van Ashbrook <[email protected]>
Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%[email protected]/
Tested-by: Karthikeyan Ramasubramanian <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: Curtis Malainey <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/compaction: optimize >0 order folio compaction with free page split.

During migration in a memory compaction, free pages are placed in an array
of page lists based on their order. But the desire

mm/compaction: optimize >0 order folio compaction with free page split.

During migration in a memory compaction, free pages are placed in an array
of page lists based on their order. But the desired free page order
(i.e., the order of a source page) might not be always present, thus
leading to migration failures and premature compaction termination. Split
a high order free pages when source migration page has a lower order to
increase migration successful rate.

Note: merging free pages when a migration fails and a lower order free
page is returned via compaction_free() is possible, but there is too much
work. Since the free pages are not buddy pages, it is hard to identify
these free pages using existing PFN-based page merging algorithm.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zi Yan <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/compaction: add support for >0 order folio memory compaction.

Before last commit, memory compaction only migrates order-0 folios and
skips >0 order folios. Last commit splits all >0 order folios

mm/compaction: add support for >0 order folio memory compaction.

Before last commit, memory compaction only migrates order-0 folios and
skips >0 order folios. Last commit splits all >0 order folios during
compaction. This commit migrates >0 order folios during compaction by
keeping isolated free pages at their original size without splitting them
into order-0 pages and using them directly during migration process.

What is different from the prior implementation:
1. All isolated free pages are kept in a NR_PAGE_ORDERS array of page
lists, where each page list stores free pages in the same order.
2. All free pages are not post_alloc_hook() processed nor buddy pages,
although their orders are stored in first page's private like buddy
pages.
3. During migration, in new page allocation time (i.e., in
compaction_alloc()), free pages are then processed by post_alloc_hook().
When migration fails and a new page is returned (i.e., in
compaction_free()), free pages are restored by reversing the
post_alloc_hook() operations using newly added
free_pages_prepare_fpi_none().

Step 3 is done for a latter optimization that splitting and/or merging
free pages during compaction becomes easier.

Note: without splitting free pages, compaction can end prematurely due to
migration will return -ENOMEM even if there is free pages. This happens
when no order-0 free page exist and compaction_alloc() return NULL.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zi Yan <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/compaction: enable compacting >0 order folios.

migrate_pages() supports >0 order folio migration and during compaction,
even if compaction_alloc() cannot provide >0 order free pages,
migrate_page

mm/compaction: enable compacting >0 order folios.

migrate_pages() supports >0 order folio migration and during compaction,
even if compaction_alloc() cannot provide >0 order free pages,
migrate_pages() can split the source page and try to migrate the base
pages from the split. It can be a baseline and start point for adding
support for compacting >0 order folios.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zi Yan <[email protected]>
Suggested-by: Huang Ying <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Adam Manzanares <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kemeng Shi <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yin Fengwei <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: early termination in compact_nodes()

No need to continue try compact memory if pending fatal signal, allow loop
termination earlier in compact_nodes().

The existing fatal_signal_pen

mm: compaction: early termination in compact_nodes()

No need to continue try compact memory if pending fatal signal, allow loop
termination earlier in compact_nodes().

The existing fatal_signal_pending() check does make compact_zone()
break out of the while loop, but it still enters the next zone/next
nid, and some unnecessary functions(eg, lru_add_drain) are called.
There was no observable benefit from the new test, it is just found
from code inspection when refactoring compact_node().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: limit the suitable target page order to be less than cc->order

It can not improve the fragmentation if we isolate the target free pages
exceeding cc->order, especially when the cc->o

mm: compaction: limit the suitable target page order to be less than cc->order

It can not improve the fragmentation if we isolate the target free pages
exceeding cc->order, especially when the cc->order is less than
pageblock_order. For example, suppose the pageblock_order is MAX_ORDER
(size is 4M) and cc->order is 2M THP size, we should not isolate other 2M
free pages to be the migration target, which can not improve the
fragmentation.

Moreover this is also applicable for large folio compaction.

Link: https://lkml.kernel.org/r/afcd9377351c259df7a25a388a4a0d5862b986f4.1705928395.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: refactor compact_node()

Refactor compact_node() to handle both proactive and synchronous compact
memory, which cleanups code a bit.

Link: https://lkml.kernel.org/r/20240208013607.17

mm: compaction: refactor compact_node()

Refactor compact_node() to handle both proactive and synchronous compact
memory, which cleanups code a bit.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages

Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison
to ensure that enough freepages are

mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages

Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison
to ensure that enough freepages are isolated in isolate_freepages(),
however it just decreases the cc->nr_freepages without updating
cc->nr_migratepages in compaction_alloc(), which will waste more CPU
cycles and cause too many freepages to be isolated.

So we should also update the cc->nr_migratepages when allocating or
freeing the freepages to avoid isolating excess freepages. And I can see
fewer free pages are scanned and isolated when running thpcompact on my
Arm64 server:

k6.7 k6.7_patched
Ops Compaction pages isolated 120692036.00 118160797.00
Ops Compaction migrate scanned 131210329.00 154093268.00
Ops Compaction free scanned 1090587971.00 1080632536.00
Ops Compact scan efficiency 12.03 14.26

Moreover, I did not see an obvious latency improvements, this is likely
because isolating freepages is not the bottleneck in the thpcompact test
case.

k6.7 k6.7_patched
Amean fault-both-1 1089.76 ( 0.00%) 1080.16 * 0.88%*
Amean fault-both-3 1616.48 ( 0.00%) 1636.65 * -1.25%*
Amean fault-both-5 2266.66 ( 0.00%) 2219.20 * 2.09%*
Amean fault-both-7 2909.84 ( 0.00%) 2801.90 * 3.71%*
Amean fault-both-12 4861.26 ( 0.00%) 4733.25 * 2.63%*
Amean fault-both-18 7351.11 ( 0.00%) 6950.51 * 5.45%*
Amean fault-both-24 9059.30 ( 0.00%) 9159.99 * -1.11%*
Amean fault-both-30 10685.68 ( 0.00%) 11399.02 * -6.68%*

Link: https://lkml.kernel.org/r/6440493f18da82298152b6305d6b41c2962a3ce6.1708409245.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...