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mm/damon/ops-common: atomically test and clear young on ptes and pmds 

commit c11d34fa13 upstream.

It is racy to non-atomically read a pte, then clear the young bit, then
write it back as this could discard dirty information.  Further, it is bad
practice to directly set a pte entry within a table.  Instead clearing
young must go through the arch-provided helper,
ptep_test_and_clear_young() to ensure it is modified atomically and to
give the arch code visibility and allow it to check (and potentially
modify) the operation.

Link: https://lkml.kernel.org/r/20230602092949.545577-3-ryan.roberts@arm.com
Fixes: 3f49584b26 ("mm/damon: implement primitives for the virtual memory address spaces").
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ryan Roberts 2023-06-02 10:29:47 +01:00 committed by Greg Kroah-Hartman
parent 7efc5bee24
commit 7eeed3ed1a
1 changed files with 8 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
mm/damon/vaddr.c
View File

@ -393,7 +393,7 @@ static struct page *damon_get_page(unsigned long pfn)
return page;
}
static void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm,
static void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma,
unsigned long addr)
{
bool referenced = false;
@ -402,13 +402,11 @@ static void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm,
if (!page)
return;
if (pte_young(*pte)) {
if (ptep_test_and_clear_young(vma, addr, pte))
referenced = true;
*pte = pte_mkold(*pte);
}
#ifdef CONFIG_MMU_NOTIFIER
if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
if (mmu_notifier_clear_young(vma->vm_mm, addr, addr + PAGE_SIZE))
referenced = true;
#endif /* CONFIG_MMU_NOTIFIER */
@ -419,7 +417,7 @@ static void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm,
put_page(page);
}
static void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm,
static void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma,
unsigned long addr)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@ -429,13 +427,11 @@ static void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm,
if (!page)
return;
if (pmd_young(*pmd)) {
if (pmdp_test_and_clear_young(vma, addr, pmd))
referenced = true;
*pmd = pmd_mkold(*pmd);
}
#ifdef CONFIG_MMU_NOTIFIER
if (mmu_notifier_clear_young(mm, addr,
if (mmu_notifier_clear_young(vma->vm_mm, addr,
addr + ((1UL) << HPAGE_PMD_SHIFT)))
referenced = true;
#endif /* CONFIG_MMU_NOTIFIER */
@ -462,7 +458,7 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,
}
if (pmd_huge(*pmd)) {
damon_pmdp_mkold(pmd, walk->mm, addr);
damon_pmdp_mkold(pmd, walk->vma, addr);
spin_unlock(ptl);
return 0;
}
@ -474,7 +470,7 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,
pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
if (!pte_present(*pte))
goto out;
damon_ptep_mkold(pte, walk->mm, addr);
damon_ptep_mkold(pte, walk->vma, addr);
out:
pte_unmap_unlock(pte, ptl);
return 0;