linux-toradex.git/mm/rmap.c, branch v5.12

mm/rmap: correct obsolete comment of page_get_anon_vma()

2021-02-26T17:41:01+00:00

Since commit 746b18d421da ("mm: use refcounts for page_lock_anon_vma()"),
page_lock_anon_vma() is renamed to page_get_anon_vma() and converted to
return a refcount increased anon_vma.  But it forgot to change the
relevant comment.

Link: https://lkml.kernel.org/r/20210203093215.31990-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/rmap: use page_not_mapped in try_to_unmap()

2021-02-26T17:41:01+00:00

page_mapcount_is_zero() calculates accurately how many mappings a hugepage
has in order to check against 0 only.  This is a waste of cpu time.  We
can do this via page_not_mapped() to save some possible atomic_read
cycles.  Remove the function page_mapcount_is_zero() as it's not used
anymore and move page_not_mapped() above try_to_unmap() to avoid
identifier undeclared compilation error.

Link: https://lkml.kernel.org/r/20210130084904.35307-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/rmap: fix obsolete comment in __page_check_anon_rmap()

2021-02-26T17:41:01+00:00

Commit 21333b2b66b8 ("ksm: no debug in page_dup_rmap()") has reverted
page_dup_rmap() to an inline atomic_inc of mapcount.  So page_dup_rmap()
does not call __page_check_anon_rmap() anymore.

Link: https://lkml.kernel.org/r/20210128110209.50857-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/rmap: remove unneeded semicolon in page_not_mapped()

2021-02-26T17:41:01+00:00

Remove extra semicolon without any functional change intended.

Link: https://lkml.kernel.org/r/20210127093425.39640-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/rmap: correct some obsolete comments of anon_vma

2021-02-26T17:41:01+00:00

commit 2b575eb64f7a ("mm: convert anon_vma->lock to a mutex") changed
spinlock used to serialize access to vma list to mutex.  And further, the
commit 5a505085f043 ("mm/rmap: Convert the struct anon_vma::mutex to an
rwsem") converted the mutex to an rwsem for solving scalability problem.
So replace spinlock with rwsem to make comment uptodate.

Link: https://lkml.kernel.org/r/20210123072459.25903-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin 
Cc: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas()

2021-02-24T21:38:30+00:00

In case the vma will continue to be used after unlink its relevant
anon_vma, we need to reset the vma->anon_vma pointer to NULL.  So, later
when fault happen within this vma again, a new anon_vma will be prepared.

By this way, the vma will only be checked for reverse mapping of pages
which been fault in after the unlink_anon_vmas call.

Currently, the mremap with MREMAP_DONTUNMAP scenario will continue use the
vma after moved its page table entries to a new vma.  For other scenarios,
the vma itself will be freed after call unlink_anon_vmas.

Link: https://lkml.kernel.org/r/20210119075126.3513154-1-lixinhai.lxh@gmail.com
Signed-off-by: Li Xinhai 
Cc: Andrea Arcangeli 
Cc: Brian Geffon 
Cc: Kirill A. Shutemov 
Cc: Lokesh Gidra 
Cc: Minchan Kim 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: convert NR_FILE_PMDMAPPED account to pages

2021-02-24T21:38:29+00:00

Currently we use struct per_cpu_nodestat to cache the vmstat counters,
which leads to inaccurate statistics especially THP vmstat counters.  In
the systems with hundreds of processors it can be GBs of memory.  For
example, for a 96 CPUs system, the threshold is the maximum number of 125.
And the per cpu counters can cache 23.4375 GB in total.

The THP page is already a form of batched addition (it will add 512 worth
of memory in one go) so skipping the batching seems like sensible.
Although every THP stats update overflows the per-cpu counter, resorting
to atomic global updates.  But it can make the statistics more accuracy
for the THP vmstat counters.

So we convert the NR_FILE_PMDMAPPED account to pages.  This patch is
consistent with 8f182270dfec ("mm/swap.c: flush lru pvecs on compound page
arrival").  Doing this also can make the unit of vmstat counters more
unified.  Finally, the unit of the vmstat counters are pages, kB and
bytes.  The B/KB suffix can tell us that the unit is bytes or kB.  The
rest which is without suffix are pages.

Link: https://lkml.kernel.org/r/20201228164110.2838-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Cc: Alexey Dobriyan 
Cc: Feng Tang 
Cc: Greg Kroah-Hartman 
Cc: Hugh Dickins 
Cc: Johannes Weiner 
Cc: Joonsoo Kim 
Cc: Michal Hocko 
Cc: NeilBrown 
Cc: Pankaj Gupta 
Cc: Rafael. J. Wysocki 
Cc: Randy Dunlap 
Cc: Roman Gushchin 
Cc: Sami Tolvanen 
Cc: Shakeel Butt 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: convert NR_SHMEM_PMDMAPPED account to pages

2021-02-24T21:38:29+00:00

Currently we use struct per_cpu_nodestat to cache the vmstat counters,
which leads to inaccurate statistics especially THP vmstat counters.  In
the systems with hundreds of processors it can be GBs of memory.  For
example, for a 96 CPUs system, the threshold is the maximum number of 125.
And the per cpu counters can cache 23.4375 GB in total.

The THP page is already a form of batched addition (it will add 512 worth
of memory in one go) so skipping the batching seems like sensible.
Although every THP stats update overflows the per-cpu counter, resorting
to atomic global updates.  But it can make the statistics more accuracy
for the THP vmstat counters.

So we convert the NR_SHMEM_PMDMAPPED account to pages.  This patch is
consistent with 8f182270dfec ("mm/swap.c: flush lru pvecs on compound page
arrival").  Doing this also can make the unit of vmstat counters more
unified.  Finally, the unit of the vmstat counters are pages, kB and
bytes.  The B/KB suffix can tell us that the unit is bytes or kB.  The
rest which is without suffix are pages.

Link: https://lkml.kernel.org/r/20201228164110.2838-6-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Cc: Alexey Dobriyan 
Cc: Feng Tang 
Cc: Greg Kroah-Hartman 
Cc: Hugh Dickins 
Cc: Johannes Weiner 
Cc: Joonsoo Kim 
Cc: Michal Hocko 
Cc: NeilBrown 
Cc: Pankaj Gupta 
Cc: Rafael. J. Wysocki 
Cc: Randy Dunlap 
Cc: Roman Gushchin 
Cc: Sami Tolvanen 
Cc: Shakeel Butt 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: convert NR_ANON_THPS account to pages

2021-02-24T21:38:29+00:00

Currently we use struct per_cpu_nodestat to cache the vmstat counters,
which leads to inaccurate statistics especially THP vmstat counters.  In
the systems with hundreds of processors it can be GBs of memory.  For
example, for a 96 CPUs system, the threshold is the maximum number of 125.
And the per cpu counters can cache 23.4375 GB in total.

The THP page is already a form of batched addition (it will add 512 worth
of memory in one go) so skipping the batching seems like sensible.
Although every THP stats update overflows the per-cpu counter, resorting
to atomic global updates.  But it can make the statistics more accuracy
for the THP vmstat counters.

So we convert the NR_ANON_THPS account to pages.  This patch is consistent
with 8f182270dfec ("mm/swap.c: flush lru pvecs on compound page arrival").
Doing this also can make the unit of vmstat counters more unified.
Finally, the unit of the vmstat counters are pages, kB and bytes.  The
B/KB suffix can tell us that the unit is bytes or kB.  The rest which is
without suffix are pages.

Link: https://lkml.kernel.org/r/20201228164110.2838-3-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Cc: Greg Kroah-Hartman 
Cc: Rafael. J. Wysocki 
Cc: Alexey Dobriyan 
Cc: Johannes Weiner 
Cc: Vladimir Davydov 
Cc: Hugh Dickins 
Cc: Shakeel Butt 
Cc: Roman Gushchin 
Cc: Sami Tolvanen 
Cc: Feng Tang 
Cc: NeilBrown 
Cc: Joonsoo Kim 
Cc: Randy Dunlap 
Cc: Michal Hocko 
Cc: Pankaj Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/lru: revise the comments of lru_lock

2020-12-15T22:48:04+00:00

Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to fix
the incorrect comments in code.  Also fixed some zone->lru_lock comment
error from ancient time.  etc.

I struggled to understand the comment above move_pages_to_lru() (surely
it never calls page_referenced()), and eventually realized that most of
it had got separated from shrink_active_list(): move that comment back.

Link: https://lkml.kernel.org/r/1604566549-62481-20-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Hugh Dickins 
Signed-off-by: Alex Shi 
Acked-by: Johannes Weiner 
Acked-by: Vlastimil Babka 
Cc: Tejun Heo 
Cc: Andrey Ryabinin 
Cc: Jann Horn 
Cc: Mel Gorman 
Cc: Matthew Wilcox 
Cc: Alexander Duyck 
Cc: Andrea Arcangeli 
Cc: "Chen, Rong A" 
Cc: Daniel Jordan 
Cc: "Huang, Ying" 
Cc: Joonsoo Kim 
Cc: Kirill A. Shutemov 
Cc: Kirill A. Shutemov 
Cc: Konstantin Khlebnikov 
Cc: Michal Hocko 
Cc: Michal Hocko 
Cc: Mika Penttilä 
Cc: Minchan Kim 
Cc: Shakeel Butt 
Cc: Thomas Gleixner 
Cc: Vladimir Davydov 
Cc: Wei Yang 
Cc: Yang Shi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds