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

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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").
Change-Id: I592151dc02b7f9e3aaa50aab65c4373f4d1671fd
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>
(cherry picked from commit 7eeed3ed1a)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Greg Kroah-Hartman
2023-08-03 14:18:00 +00:00
parent 9f5bde3ccf
commit 4b20633d79
3 changed files with 10 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
mm/damon/paddr.c
View File

@@ -28,9 +28,9 @@ static bool __damon_pa_mkold(struct page *page, struct vm_area_struct *vma,
while (page_vma_mapped_walk(&pvmw)) {
addr = pvmw.address;
if (pvmw.pte)
damon_ptep_mkold(pvmw.pte, vma->vm_mm, addr);
damon_ptep_mkold(pvmw.pte, vma, addr);
else
damon_pmdp_mkold(pvmw.pmd, vma->vm_mm, addr);
damon_pmdp_mkold(pvmw.pmd, vma, addr);
}
return true;
}

16
mm/damon/prmtv-common.c
View File

@@ -33,7 +33,7 @@ struct page *damon_get_page(unsigned long pfn)
return page;
}
void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr)
{
bool referenced = false;
struct page *page = damon_get_page(pte_pfn(*pte));
@@ -41,13 +41,11 @@ void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
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 */
@@ -58,7 +56,7 @@ void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
put_page(page);
}
void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
bool referenced = false;
@@ -67,13 +65,11 @@ void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
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 */

4
mm/damon/prmtv-common.h
View File

@@ -9,8 +9,8 @@
struct page *damon_get_page(unsigned long pfn);
void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr);
void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr);
void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr);
void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr);
int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
struct damos *s);