The patch titled
Subject: mm: fix NUMA node file count error in replace_page_cache()
has been added to the -mm tree. Its filename is
mm-fix-numa-node-file-count-error-in-replace_page_cache.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-numa-node-file-count-error-in-replace_page_cache.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-numa-node-file-count-error-in-replace_page_cache.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: fix NUMA node file count error in replace_page_cache()
Patch series "mm: memcontrol: charge swapin pages on instantiation", v2.
This patch series reworks memcg to charge swapin pages directly at
swapin time, rather than at fault time, which may be much later, or
not happen at all.
Changes in version 2:
- prevent double charges on pre-allocated hugepages in khugepaged
- leave shmem swapcache when charging fails to avoid double IO (Joonsoo)
- fix temporary accounting bug by switching rmap<->commit (Joonsoo)
- fix double swap charge bug in cgroup1/cgroup2 code gating
- simplify swapin error checking (Joonsoo)
- mm: memcontrol: document the new swap control behavior (Alex)
- review tags
The delayed swapin charging scheme we have right now causes problems:
- Alex's per-cgroup lru_lock patches rely on pages that have been
isolated from the LRU to have a stable page->mem_cgroup; otherwise
the lock may change underneath him. Swapcache pages are charged only
after they are added to the LRU, and charging doesn't follow the LRU
isolation protocol.
- Joonsoo's anon workingset patches need a suitable LRU at the time
the page enters the swap cache and displaces the non-resident
info. But the correct LRU is only available after charging.
- It's a containment hole / DoS vector. Users can trigger arbitrarily
large swap readahead using MADV_WILLNEED. The memory is never
charged unless somebody actually touches it.
- It complicates the page->mem_cgroup stabilization rules
In order to charge pages directly at swapin time, the memcg code base
needs to be prepared, and several overdue cleanups become a necessity:
To charge pages at swapin time, we need to always have cgroup
ownership tracking of swap records. We also cannot rely on
page->mapping to tell apart page types at charge time, because that's
only set up during a page fault.
To eliminate the page->mapping dependency, memcg needs to ditch its
private page type counters (MEMCG_CACHE, MEMCG_RSS, NR_SHMEM) in favor
of the generic vmstat counters and accounting sites, such as
NR_FILE_PAGES, NR_ANON_MAPPED etc.
To switch to generic vmstat counters, the charge sequence must be
adjusted such that page->mem_cgroup is set up by the time these
counters are modified.
The series is structured as follows:
1. Bug fixes
2. Decoupling charging from rmap
3. Swap controller integration into memcg
4. Direct swapin charging
This patch (of 19):
When replacing one page with another one in the cache, we have to decrease
the file count of the old page's NUMA node and increase the one of the new
NUMA node, otherwise the old node leaks the count and the new node
eventually underflows its counter.
Link: http://lkml.kernel.org/r/20200508183105.225460-1-hannes@xxxxxxxxxxx
Link: http://lkml.kernel.org/r/20200508183105.225460-2-hannes@xxxxxxxxxxx
Fixes: 74d609585d8b ("page cache: Add and replace pages using the XArray")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/filemap.c~mm-fix-numa-node-file-count-error-in-replace_page_cache
+++ a/mm/filemap.c
@@ -808,11 +808,11 @@ int replace_page_cache_page(struct page
old->mapping = NULL;
/* hugetlb pages do not participate in page cache accounting. */
if (!PageHuge(old))
- __dec_node_page_state(new, NR_FILE_PAGES);
+ __dec_node_page_state(old, NR_FILE_PAGES);
if (!PageHuge(new))
__inc_node_page_state(new, NR_FILE_PAGES);
if (PageSwapBacked(old))
- __dec_node_page_state(new, NR_SHMEM);
+ __dec_node_page_state(old, NR_SHMEM);
if (PageSwapBacked(new))
__inc_node_page_state(new, NR_SHMEM);
xas_unlock_irqrestore(&xas, flags);
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-fix-numa-node-file-count-error-in-replace_page_cache.patch
mm-memcontrol-fix-stat-corrupting-race-in-charge-moving.patch
mm-memcontrol-drop-compound-parameter-from-memcg-charging-api.patch
mm-memcontrol-move-out-cgroup-swaprate-throttling.patch
mm-memcontrol-convert-page-cache-to-a-new-mem_cgroup_charge-api.patch
mm-memcontrol-prepare-uncharging-for-removal-of-private-page-type-counters.patch
mm-memcontrol-prepare-move_account-for-removal-of-private-page-type-counters.patch
mm-memcontrol-prepare-cgroup-vmstat-infrastructure-for-native-anon-counters.patch
mm-memcontrol-switch-to-native-nr_file_pages-and-nr_shmem-counters.patch
mm-memcontrol-switch-to-native-nr_anon_mapped-counter.patch
mm-memcontrol-switch-to-native-nr_anon_thps-counter.patch
mm-memcontrol-convert-anon-and-file-thp-to-new-mem_cgroup_charge-api.patch
mm-memcontrol-drop-unused-try-commit-cancel-charge-api.patch
mm-memcontrol-prepare-swap-controller-setup-for-integration.patch
mm-memcontrol-make-swap-tracking-an-integral-part-of-memory-control.patch
mm-memcontrol-charge-swapin-pages-on-instantiation.patch
mm-memcontrol-delete-unused-lrucare-handling.patch
mm-memcontrol-update-page-mem_cgroup-stability-rules.patch
