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rmap: do not call mmu_notifier_invalidate_page() under ptl
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MMU notifiers can sleep, but in page_mkclean_one() we call
mmu_notifier_invalidate_page() under page table lock.

Let's instead use mmu_notifier_invalidate_range() outside
page_vma_mapped_walk() loop.

[jglisse@redhat.com: try_to_unmap_one() do not call mmu_notifier under ptl]
  Link: http://lkml.kernel.org/r/20170809204333.27485-1-jglisse@redhat.com
Link: http://lkml.kernel.org/r/20170804134928.l4klfcnqatni7vsc@black.fi.intel.com
Fixes: c7ab0d2 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reported-by: axie <axie@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Writer, Tim" <Tim.Writer@amd.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@kiryl @torvalds
kiryl authored and torvalds committed Aug 10, 2017
1 parent d041353 commit aac2fea
Showing 1 changed file with 30 additions and 22 deletions.
52 changes: 30 additions & 22 deletions mm/rmap.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -888,22 +888,22 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
.flags = PVMW_SYNC,
};
int *cleaned = arg;
bool invalidation_needed = false;

while (page_vma_mapped_walk(&pvmw)) {
int ret = 0;
address = pvmw.address;
if (pvmw.pte) {
pte_t entry;
pte_t *pte = pvmw.pte;

if (!pte_dirty(*pte) && !pte_write(*pte))
continue;

flush_cache_page(vma, address, pte_pfn(*pte));
entry = ptep_clear_flush(vma, address, pte);
flush_cache_page(vma, pvmw.address, pte_pfn(*pte));
entry = ptep_clear_flush(vma, pvmw.address, pte);
entry = pte_wrprotect(entry);
entry = pte_mkclean(entry);
set_pte_at(vma->vm_mm, address, pte, entry);
set_pte_at(vma->vm_mm, pvmw.address, pte, entry);
ret = 1;
} else {
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
Expand All @@ -913,11 +913,11 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
continue;

flush_cache_page(vma, address, page_to_pfn(page));
entry = pmdp_huge_clear_flush(vma, address, pmd);
flush_cache_page(vma, pvmw.address, page_to_pfn(page));
entry = pmdp_huge_clear_flush(vma, pvmw.address, pmd);
entry = pmd_wrprotect(entry);
entry = pmd_mkclean(entry);
set_pmd_at(vma->vm_mm, address, pmd, entry);
set_pmd_at(vma->vm_mm, pvmw.address, pmd, entry);
ret = 1;
#else
/* unexpected pmd-mapped page? */
Expand All @@ -926,11 +926,16 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
}

if (ret) {
mmu_notifier_invalidate_page(vma->vm_mm, address);
(*cleaned)++;
invalidation_needed = true;
}
}

if (invalidation_needed) {
mmu_notifier_invalidate_range(vma->vm_mm, address,
address + (1UL << compound_order(page)));
}

return true;
}

Expand Down Expand Up @@ -1323,7 +1328,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
};
pte_t pteval;
struct page *subpage;
bool ret = true;
bool ret = true, invalidation_needed = false;
enum ttu_flags flags = (enum ttu_flags)arg;

/* munlock has nothing to gain from examining un-locked vmas */
Expand Down Expand Up @@ -1363,11 +1368,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
VM_BUG_ON_PAGE(!pvmw.pte, page);

subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
address = pvmw.address;


if (!(flags & TTU_IGNORE_ACCESS)) {
if (ptep_clear_flush_young_notify(vma, address,
if (ptep_clear_flush_young_notify(vma, pvmw.address,
pvmw.pte)) {
ret = false;
page_vma_mapped_walk_done(&pvmw);
Expand All @@ -1376,7 +1379,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
}

/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
flush_cache_page(vma, pvmw.address, pte_pfn(*pvmw.pte));
if (should_defer_flush(mm, flags)) {
/*
* We clear the PTE but do not flush so potentially
Expand All @@ -1386,11 +1389,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
* transition on a cached TLB entry is written through
* and traps if the PTE is unmapped.
*/
pteval = ptep_get_and_clear(mm, address, pvmw.pte);
pteval = ptep_get_and_clear(mm, pvmw.address,
pvmw.pte);

set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
} else {
pteval = ptep_clear_flush(vma, address, pvmw.pte);
pteval = ptep_clear_flush(vma, pvmw.address, pvmw.pte);
}

/* Move the dirty bit to the page. Now the pte is gone. */
Expand All @@ -1405,12 +1409,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
if (PageHuge(page)) {
int nr = 1 << compound_order(page);
hugetlb_count_sub(nr, mm);
set_huge_swap_pte_at(mm, address,
set_huge_swap_pte_at(mm, pvmw.address,
pvmw.pte, pteval,
vma_mmu_pagesize(vma));
} else {
dec_mm_counter(mm, mm_counter(page));
set_pte_at(mm, address, pvmw.pte, pteval);
set_pte_at(mm, pvmw.address, pvmw.pte, pteval);
}

} else if (pte_unused(pteval)) {
Expand All @@ -1434,7 +1438,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
swp_pte = swp_entry_to_pte(entry);
if (pte_soft_dirty(pteval))
swp_pte = pte_swp_mksoft_dirty(swp_pte);
set_pte_at(mm, address, pvmw.pte, swp_pte);
set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
} else if (PageAnon(page)) {
swp_entry_t entry = { .val = page_private(subpage) };
pte_t swp_pte;
Expand All @@ -1460,15 +1464,15 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
* If the page was redirtied, it cannot be
* discarded. Remap the page to page table.
*/
set_pte_at(mm, address, pvmw.pte, pteval);
set_pte_at(mm, pvmw.address, pvmw.pte, pteval);
SetPageSwapBacked(page);
ret = false;
page_vma_mapped_walk_done(&pvmw);
break;
}

if (swap_duplicate(entry) < 0) {
set_pte_at(mm, address, pvmw.pte, pteval);
set_pte_at(mm, pvmw.address, pvmw.pte, pteval);
ret = false;
page_vma_mapped_walk_done(&pvmw);
break;
Expand All @@ -1484,14 +1488,18 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
swp_pte = swp_entry_to_pte(entry);
if (pte_soft_dirty(pteval))
swp_pte = pte_swp_mksoft_dirty(swp_pte);
set_pte_at(mm, address, pvmw.pte, swp_pte);
set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
} else
dec_mm_counter(mm, mm_counter_file(page));
discard:
page_remove_rmap(subpage, PageHuge(page));
put_page(page);
mmu_notifier_invalidate_page(mm, address);
invalidation_needed = true;
}

if (invalidation_needed)
mmu_notifier_invalidate_range(mm, address,
address + (1UL << compound_order(page)));
return ret;
}

Expand Down

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