| Message ID | 20200903183140.19055-1-rcampbell@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] mm/thp: fix __split_huge_pmd_locked() for migration PMD | expand |
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This commit has been processed because it contains a "Fixes:" tag
fixing commit: 84c3fc4e9c56 ("mm: thp: check pmd migration entry in common path").
The bot has tested the following trees: v5.8.6, v5.4.62, v4.19.143, v4.14.196.
v5.8.6: Build OK!
v5.4.62: Failed to apply! Possible dependencies:
0d1c20722ab3 ("mm: memcontrol: switch to native NR_FILE_PAGES and NR_SHMEM counters")
3fba69a56e16 ("mm: memcontrol: drop @compound parameter from memcg charging API")
468c398233da ("mm: memcontrol: switch to native NR_ANON_THPS counter")
72981e0e7b60 ("userfaultfd: wp: add UFFDIO_COPY_MODE_WP")
83d116c53058 ("mm: fix double page fault on arm64 if PTE_AF is cleared")
85b9f46e8ea4 ("mm, thp: track fallbacks due to failed memcg charges separately")
92855270ff08 ("mm/memcontrol.c: cleanup some useless code")
be5d0a74c62d ("mm: memcontrol: switch to native NR_ANON_MAPPED counter")
c23a0c99793f ("mm/migrate: clean up some minor coding style")
dcdf11ee1441 ("mm, shmem: add vmstat for hugepage fallback")
f4129ea3591a ("mm: fix NUMA node file count error in replace_page_cache()")
ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced")
v4.19.143: Failed to apply! Possible dependencies:
0ac261042084 ("x86/irq/64: Init hardirq_stack_ptr during CPU hotplug")
0d1c20722ab3 ("mm: memcontrol: switch to native NR_FILE_PAGES and NR_SHMEM counters")
117ed4548541 ("x86/irq/64: Remove stack overflow debug code")
231c4846b106 ("x86/irq/32: Make irq stack a character array")
30842211506e ("x86/exceptions: Remove unused stack defines on 32bit")
39656e83dab9 ("mm: lift the x86_32 PAE version of gup_get_pte to common code")
468c398233da ("mm: memcontrol: switch to native NR_ANON_THPS counter")
4f44b8f0b33b ("x86/irq/64: Remove a hardcoded irq_stack_union access")
66c7ceb47f62 ("x86/irq/32: Handle irq stack allocation failure proper")
758a2e312228 ("x86/irq/64: Rename irq_stack_ptr to hardirq_stack_ptr")
7ac870747988 ("x86/vdso: Switch to generic vDSO implementation")
99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
a754fe2b76d1 ("x86/irq/32: Rename hard/softirq_stack to hard/softirq_stack_ptr")
aa641c287b2f ("x86/irq/32: Define IRQ_STACK_SIZE")
be5d0a74c62d ("mm: memcontrol: switch to native NR_ANON_MAPPED counter")
df835e7083be ("x86/irq/64: Sanitize the top/bottom confusion")
e6401c130931 ("x86/irq/64: Split the IRQ stack into its own pages")
v4.14.196: Failed to apply! Possible dependencies:
050e9baa9dc9 ("Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables")
0d1c20722ab3 ("mm: memcontrol: switch to native NR_FILE_PAGES and NR_SHMEM counters")
117ed4548541 ("x86/irq/64: Remove stack overflow debug code")
152e93af3cfe ("mm, thp: Do not make pmd/pud dirty without a reason")
2a61f4747eea ("stack-protector: test compiler capability in Kconfig and drop AUTO mode")
2b8383927525 ("Makefile: move stack-protector compiler breakage test earlier")
2bc2f688fdf8 ("Makefile: move stack-protector availability out of Kconfig")
39656e83dab9 ("mm: lift the x86_32 PAE version of gup_get_pte to common code")
44c6dc940b19 ("Makefile: introduce CONFIG_CC_STACKPROTECTOR_AUTO")
4645b9fe84bf ("mm/mmu_notifier: avoid call to invalidate_range() in range_end()")
468c398233da ("mm: memcontrol: switch to native NR_ANON_THPS counter")
59c66c5f8c4f ("mm: factor out page cache page freeing into a separate function")
5ecc4d852c03 ("mm: factor out checks and accounting from __delete_from_page_cache()")
76253fbc8fbf ("mm: move accounting updates before page_cache_tree_delete()")
7ac870747988 ("x86/vdso: Switch to generic vDSO implementation")
8373b7d9d174 ("Documentation: kconfig: add recommended way to describe compiler support")
99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
be5d0a74c62d ("mm: memcontrol: switch to native NR_ANON_MAPPED counter")
e6401c130931 ("x86/irq/64: Split the IRQ stack into its own pages")
fadae2953072 ("thp: use mm_file_counter to determine update which rss counter")
NOTE: The patch will not be queued to stable trees until it is upstream.
How should we proceed with this patch?
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2a468a4acb0a..606d712d9505 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2023,7 +2023,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, put_page(page); add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); return; - } else if (is_huge_zero_pmd(*pmd)) { + } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { /* * FIXME: Do we want to invalidate secondary mmu by calling * mmu_notifier_invalidate_range() see comments below inside @@ -2117,30 +2117,34 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, addr, pte, entry); - atomic_inc(&page[i]._mapcount); - pte_unmap(pte); - } - - /* - * Set PG_double_map before dropping compound_mapcount to avoid - * false-negative page_mapped(). - */ - if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { - for (i = 0; i < HPAGE_PMD_NR; i++) + if (!pmd_migration) atomic_inc(&page[i]._mapcount); + pte_unmap(pte); } - lock_page_memcg(page); - if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { - /* Last compound_mapcount is gone. */ - __dec_lruvec_page_state(page, NR_ANON_THPS); - if (TestClearPageDoubleMap(page)) { - /* No need in mapcount reference anymore */ + if (!pmd_migration) { + /* + * Set PG_double_map before dropping compound_mapcount to avoid + * false-negative page_mapped(). + */ + if (compound_mapcount(page) > 1 && + !TestSetPageDoubleMap(page)) { for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_dec(&page[i]._mapcount); + atomic_inc(&page[i]._mapcount); + } + + lock_page_memcg(page); + if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { + /* Last compound_mapcount is gone. */ + __dec_lruvec_page_state(page, NR_ANON_THPS); + if (TestClearPageDoubleMap(page)) { + /* No need in mapcount reference anymore */ + for (i = 0; i < HPAGE_PMD_NR; i++) + atomic_dec(&page[i]._mapcount); + } } + unlock_page_memcg(page); } - unlock_page_memcg(page); smp_wmb(); /* make pte visible before pmd */ pmd_populate(mm, pmd, pgtable);
A migrating transparent huge page has to already be unmapped. Otherwise, the page could be modified while it is being copied to a new page and data could be lost. The function __split_huge_pmd() checks for a PMD migration entry before calling __split_huge_pmd_locked() leading one to think that __split_huge_pmd_locked() can handle splitting a migrating PMD. However, the code always increments the page->_mapcount and adjusts the memory control group accounting assuming the page is mapped. Also, if the PMD entry is a migration PMD entry, the call to is_huge_zero_pmd(*pmd) is incorrect because it calls pmd_pfn(pmd) instead of migration_entry_to_pfn(pmd_to_swp_entry(pmd)). Fix these problems by checking for a PMD migration entry. Fixes: 84c3fc4e9c56 ("mm: thp: check pmd migration entry in common path") cc: stable@vger.kernel.org # 4.14+ Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Reviewed-by: Zi Yan <ziy@nvidia.com> --- No changes in v3 to this patch, just added reviewed-by and fixes to the change log and sending this as a separate patch from the rest of the series ("mm/hmm/nouveau: add THP migration to migrate_vma_*"). I'll hold off resending the series without this patch unless there are changes needed. mm/huge_memory.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-)