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| author |  David Hildenbrand <david@redhat.com>
| 2024-04-09 21:22:50 +0200 |
|---|---|---|
| committer |  Andrew Morton <akpm@linux-foundation.org>
| 2024-05-05 17:53:29 -0700 |
| commit | 3aeea4fc835d31235947787c2b8dcbc255131106 (patch) | |
| tree | 3cbf269fc37a8032a25cb8e369b07e6f36155031 /mm/memory.c | |
| parent | mm: make folio_mapcount() return 0 for small typed folios (diff) | |
| download | linux-3aeea4fc835d31235947787c2b8dcbc255131106.tar.gz linux-3aeea4fc835d31235947787c2b8dcbc255131106.tar.bz2 linux-3aeea4fc835d31235947787c2b8dcbc255131106.zip | |
mm/memory: use folio_mapcount() in zap_present_folio_ptes()
We want to limit the use of page_mapcount() to the places where it is
absolutely necessary. In zap_present_folio_ptes(), let's simply check the
folio mapcount(). If there is some issue, it will underflow at some point
either way when unmapping.
As indicated already in commit 10ebac4f95e7 ("mm/memory: optimize
unmap/zap with PTE-mapped THP"), we already documented "If we ever have a
cheap folio_mapcount(), we might just want to check for underflows
there.".
There is no change for small folios. For large folios, we'll now catch
more underflows when batch-unmapping, because instead of only testing the
mapcount of the first subpage, we'll test if the folio mapcount
underflows.
Link: https://lkml.kernel.org/r/20240409192301.907377-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Richard Chang <richardycc@google.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index 36ba94eae853..d592128d7f7d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1502,8 +1502,7 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, if (!delay_rmap) { folio_remove_rmap_ptes(folio, page, nr, vma); - /* Only sanity-check the first page in a batch. */ - if (unlikely(page_mapcount(page) < 0)) + if (unlikely(folio_mapcount(folio) < 0)) print_bad_pte(vma, addr, ptent, page); } |