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mm: mincore: use walk_page_range_vma() in do_mincore()

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Patch series "mm: convert to walk_page_range_vma() to eliminate
find_vma()", v2.

walk_page_range() performs a find_vma() lookup on each page table walk. 
For callers that already hold a valid VMA and operate on a known
single-VMA range, this lookup is redundant.  Replace walk_page_range()
with walk_page_range_vma() where the caller guarantees single-VMA
semantics.


This patch (of 4):

do_mincore() uses walk_page_range() to walk the page table.  Fortunately,
the caller always passes start/end that falls within a single VMA, so it's
safe to use the walk_page_range_vma() in do_mincore() to eliminate an
unnecessary find_vma() lookup.

Unlike walk_page_range(), walk_page_range_vma() does not call
walk_page_test(), which handles VM_PFNMAP by invoking ->pte_hole() to skip
the page table walk.  Without this check, PFNMAP PTEs would be treated as
present by mincore_pte_range(), changing the returned residency status. 
Handle VM_PFNMAP explicitly in do_mincore() to preserve the original
behavior.

[akpm@linux-foundation.org: simplify comment, per Pedro]
  Link: https://lore.kernel.org/ajP9bQhmvR9OX0VE@pedro-suse
Link: https://lore.kernel.org/20260618092845.3905740-1-wangkefeng.wang@huawei.com
Link: https://lore.kernel.org/20260618092845.3905740-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kefeng Wang
2026-06-18 17:28:42 +08:00
committed by Andrew Morton
parent 90f095b816
commit 8fb1ad47dc
1 changed files with 10 additions and 1 deletions
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11
mm/mincore.c
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@@ -258,7 +258,16 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
memset(vec, 1, pages);
return pages;
}
err = walk_page_range(vma->vm_mm, addr, end, &mincore_walk_ops, vec);
/*
* mincore historically reports PFNMAP mappings as non-resident.
*/
if (vma->vm_flags & VM_PFNMAP) {
__mincore_unmapped_range(addr, end, vma, vec);
return (end - addr) >> PAGE_SHIFT;
}
err = walk_page_range_vma(vma, addr, end, &mincore_walk_ops, vec);
if (err < 0)
return err;
return (end - addr) >> PAGE_SHIFT;