6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: David Hildenbrand <david@xxxxxxxxxx>
[ Upstream commit 2c1f057e5be63e890f2dd89e4c25ab5eef084a91 ]
We added PM_MMAP_EXCLUSIVE in 2015 via commit 77bb499bb60f ("pagemap: add
mmap-exclusive bit for marking pages mapped only here"), when THPs could
not be partially mapped and page_mapcount() returned something that was
true for all pages of the THP.
In 2016, we added support for partially mapping THPs via commit
53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping of
THPs") but missed to determine PM_MMAP_EXCLUSIVE as well per page.
Checking page_mapcount() on the head page does not tell the whole story.
We should check each individual page. In a future without per-page
mapcounts it will be different, but we'll change that to be consistent
with PTE-mapped THPs once we deal with that.
Link: https://lkml.kernel.org/r/20240607122357.115423-4-david@xxxxxxxxxx
Fixes: 53f9263baba6 ("mm: rework mapcount accounting to enable 4k mapping of THPs")
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/proc/task_mmu.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index a5a946bef0ac4..59571737e1677 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1470,6 +1470,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
ptl = pmd_trans_huge_lock(pmdp, vma);
if (ptl) {
+ unsigned int idx = (addr & ~PMD_MASK) >> PAGE_SHIFT;
u64 flags = 0, frame = 0;
pmd_t pmd = *pmdp;
struct page *page = NULL;
@@ -1486,8 +1487,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
if (pmd_uffd_wp(pmd))
flags |= PM_UFFD_WP;
if (pm->show_pfn)
- frame = pmd_pfn(pmd) +
- ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ frame = pmd_pfn(pmd) + idx;
}
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
else if (is_swap_pmd(pmd)) {
@@ -1496,11 +1496,9 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
if (pm->show_pfn) {
if (is_pfn_swap_entry(entry))
- offset = swp_offset_pfn(entry);
+ offset = swp_offset_pfn(entry) + idx;
else
- offset = swp_offset(entry);
- offset = offset +
- ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ offset = swp_offset(entry) + idx;
frame = swp_type(entry) |
(offset << MAX_SWAPFILES_SHIFT);
}
@@ -1516,12 +1514,16 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
if (page && !PageAnon(page))
flags |= PM_FILE;
- if (page && (flags & PM_PRESENT) && page_mapcount(page) == 1)
- flags |= PM_MMAP_EXCLUSIVE;
- for (; addr != end; addr += PAGE_SIZE) {
- pagemap_entry_t pme = make_pme(frame, flags);
+ for (; addr != end; addr += PAGE_SIZE, idx++) {
+ unsigned long cur_flags = flags;
+ pagemap_entry_t pme;
+
+ if (page && (flags & PM_PRESENT) &&
+ page_mapcount(page + idx) == 1)
+ cur_flags |= PM_MMAP_EXCLUSIVE;
+ pme = make_pme(frame, cur_flags);
err = add_to_pagemap(&pme, pm);
if (err)
break;
--
2.43.0
