On Mon, 12 Dec 2022, Greg Kroah-Hartman wrote:
From: Alex Shi alex.shi@linux.alibaba.com
[ Upstream commit 3db19aa39bac33f2e850fa1ddd67be29b192e51f ]
In the func munlock_vma_page, comments mentained lru_lock needed for serialization with split_huge_pages. But the page must be PageLocked as well as pages in split_huge_page series funcs. Thus the PageLocked is enough to serialize both funcs.
Further more, Hugh Dickins pointed: before splitting in split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes which protect the page from munlock. Thus, no needs to guard __split_huge_page_tail for mlock clean, just keep the lru_lock there for isolation purpose.
LKP found a preempt issue on __mod_zone_page_state which need change to mod_zone_page_state. Thanks!
Link: https://lkml.kernel.org/r/1604566549-62481-13-git-send-email-alex.shi@linux.... Signed-off-by: Alex Shi alex.shi@linux.alibaba.com Acked-by: Hugh Dickins hughd@google.com Acked-by: Johannes Weiner hannes@cmpxchg.org Acked-by: Vlastimil Babka vbabka@suse.cz Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Alexander Duyck alexander.duyck@gmail.com Cc: Andrea Arcangeli aarcange@redhat.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: "Chen, Rong A" rong.a.chen@intel.com Cc: Daniel Jordan daniel.m.jordan@oracle.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Jann Horn jannh@google.com Cc: Joonsoo Kim iamjoonsoo.kim@lge.com Cc: Kirill A. Shutemov kirill@shutemov.name Cc: Konstantin Khlebnikov khlebnikov@yandex-team.ru Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Michal Hocko mhocko@kernel.org Cc: Michal Hocko mhocko@suse.com Cc: Mika Penttilä mika.penttila@nextfour.com Cc: Minchan Kim minchan@kernel.org Cc: Shakeel Butt shakeelb@google.com Cc: Tejun Heo tj@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Wei Yang richard.weiyang@gmail.com Cc: Yang Shi yang.shi@linux.alibaba.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Stable-dep-of: 829ae0f81ce0 ("mm: migrate: fix THP's mapcount on isolation") Signed-off-by: Sasha Levin sashal@kernel.org
NAK from me to patches 001 through 007 here: 001 through 006 are a risky subset of patches and followups to a per-memcg per-node lru_lock series from Alex Shi, which made subtle changes to locking, memcg charging, lru management, page migration etc.
The whole series could be backported to 5.10 (I did so myself for internal usage), but cherry-picking parts of it into 5.10-stable is misguided and contrary to stable principles.
Maybe there is in fact nothing wrong with the selection made: but then give linux-mm guys two or three weeks to review and test and give the thumbs up to that selection.
Much easier, quicker and safer would be to adjust 007 (I presume the reason behind 001 through 006) to fit the 5.10-stable tree: I can do that myself if you ask, but not until later this week.
Hugh
mm/mlock.c | 26 +++++--------------------- 1 file changed, 5 insertions(+), 21 deletions(-)
diff --git a/mm/mlock.c b/mm/mlock.c index 884b1216da6a..796c726a0407 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -187,40 +187,24 @@ static void __munlock_isolation_failed(struct page *page) unsigned int munlock_vma_page(struct page *page) { int nr_pages;
- pg_data_t *pgdat = page_pgdat(page);
/* For try_to_munlock() and to serialize with page migration */ BUG_ON(!PageLocked(page));
- VM_BUG_ON_PAGE(PageTail(page), page);
- /*
* Serialize with any parallel __split_huge_page_refcount() which* might otherwise copy PageMlocked to part of the tail pages before* we clear it in the head page. It also stabilizes thp_nr_pages().*/- spin_lock_irq(&pgdat->lru_lock);
- if (!TestClearPageMlocked(page)) { /* Potentially, PTE-mapped THP: do not skip the rest PTEs */
nr_pages = 1;goto unlock_out;
return 0;nr_pages = thp_nr_pages(page);
- __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
- mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
- if (__munlock_isolate_lru_page(page, true)) {
spin_unlock_irq(&pgdat->lru_lock);
- if (!isolate_lru_page(page)) __munlock_isolated_page(page);
goto out;- }
- __munlock_isolation_failed(page);
-unlock_out:
- spin_unlock_irq(&pgdat->lru_lock);
- else
__munlock_isolation_failed(page);-out: return nr_pages - 1; } -- 2.35.1