mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-08-30 21:39:35 -04:00
Code Issues Packages Projects Releases Wiki Activity

mm: mincore: remove special handling for VM_PFNMAP

Browse Source 
As David pointed out, "it's hard to believe that someone depends on pages
in VM_PFNMAP to *not* be present", so remove the historical behavior that
always reports VM_PFNMAP pages as non-resident.

Adding mincore_pud_range() allows the page table walker to traverse the
full page table hierarchy without splitting a huge PUD, enabling much more
precise identification of resident pages in PFNMAP VMAs.

[wangkefeng.wang@huawei.com: address David's comments]
  Link: https://lore.kernel.org/20260720124151.1483820-1-wangkefeng.wang@huawei.com
Link: https://lore.kernel.org/linux-mm/0e619d71-1c3d-4534-8376-2982c7348c31@kernel.org/
Link: https://lore.kernel.org/20260717091347.1144789-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kefeng Wang
2026-07-17 17:13:43 +08:00
committed by Andrew Morton
parent 8a2081d845
commit 006943a9b4
1 changed files with 15 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
mm/mincore.c
View File

@@ -160,6 +160,20 @@ static int mincore_unmapped_range(unsigned long addr, unsigned long end,
return 0;
}
static int mincore_pud_entry(pud_t *pudp, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
if (pud_is_huge(pudp_get(pudp))) {
const unsigned long nr = (end - addr) >> PAGE_SHIFT;
memset(walk->private, 1, nr);
walk->private += nr;
walk->action = ACTION_CONTINUE;
}
return 0;
}
static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
@@ -232,6 +246,7 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)
}
static const struct mm_walk_ops mincore_walk_ops = {
.pud_entry = mincore_pud_entry,
.pmd_entry = mincore_pte_range,
.pte_hole = mincore_unmapped_range,
.hugetlb_entry = mincore_hugetlb,
@@ -259,14 +274,6 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
return pages;
}
/*
* 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;