[PATCH OLK-6.6 0/2] mm/smaps: fix race between smaps_hugetlb_range and migration
David Hildenbrand (1): fs/proc/task_mmu: convert smaps_hugetlb_range() to work on folios Jinjiang Tu (1): mm/smaps: fix race between smaps_hugetlb_range and migration fs/proc/task_mmu.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) -- 2.43.0
From: David Hildenbrand <david@redhat.com> mainline inclusion from mainline-v6.10-rc1 commit 6401a2e6900843a77a27873c0529dea68f61193d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICRU7W Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------- Let's get rid of another page_mapcount() check and simply use folio_likely_mapped_shared(), which is precise for hugetlb folios. While at it, use huge_ptep_get() + pte_page() instead of ptep_get() + vm_normal_page(), just like we do in pagemap_hugetlb_range(). No functional change intended. Link: https://lkml.kernel.org/r/20240417092313.753919-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- fs/proc/task_mmu.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 46b4c39a12db..98e1a2ef25af 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -727,19 +727,20 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, { struct mem_size_stats *mss = walk->private; struct vm_area_struct *vma = walk->vma; - struct page *page = NULL; - pte_t ptent = ptep_get(pte); + pte_t ptent = huge_ptep_get(pte); + struct folio *folio = NULL; if (pte_present(ptent)) { - page = vm_normal_page(vma, addr, ptent); + folio = page_folio(pte_page(ptent)); } else if (is_swap_pte(ptent)) { swp_entry_t swpent = pte_to_swp_entry(ptent); if (is_pfn_swap_entry(swpent)) - page = pfn_swap_entry_to_page(swpent); + folio = pfn_swap_entry_folio(swpent); } - if (page) { - if (page_mapcount(page) >= 2 || hugetlb_pmd_shared(pte)) + if (folio) { + if (folio_likely_mapped_shared(folio) || + hugetlb_pmd_shared(pte)) mss->shared_hugetlb += huge_page_size(hstate_vma(vma)); else mss->private_hugetlb += huge_page_size(hstate_vma(vma)); -- 2.43.0
mainline inclusion from mainline-v6.17-rc2 commit 45d19b4b6c2d422771c29b83462d84afcbb33f01 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICRU7W Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- smaps_hugetlb_range() handles the pte without holdling ptl, and may be concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). The race is as follows. smaps_hugetlb_range migrate_pages huge_ptep_get remove_migration_ptes folio_unlock pfn_swap_entry_folio BUG_ON To fix it, hold ptl lock in smaps_hugetlb_range(). Link: https://lkml.kernel.org/r/20250724090958.455887-1-tujinjiang@huawei.com Link: https://lkml.kernel.org/r/20250724090958.455887-2-tujinjiang@huawei.com Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps") Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Andrei Vagin <avagin@gmail.com> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Brahmajit Das <brahmajit.xyz@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: David Rientjes <rientjes@google.com> Cc: Dev Jain <dev.jain@arm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joern Engel <joern@logfs.org> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Thiago Jung Bauermann <thiago.bauermann@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Conflicts: fs/proc/task_mmu.c [Context conflicts] Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- fs/proc/task_mmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 98e1a2ef25af..8a691365061c 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -727,9 +727,12 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, { struct mem_size_stats *mss = walk->private; struct vm_area_struct *vma = walk->vma; - pte_t ptent = huge_ptep_get(pte); struct folio *folio = NULL; + spinlock_t *ptl; + pte_t ptent; + ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte); + ptent = huge_ptep_get(pte); if (pte_present(ptent)) { folio = page_folio(pte_page(ptent)); } else if (is_swap_pte(ptent)) { @@ -745,6 +748,7 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask, else mss->private_hugetlb += huge_page_size(hstate_vma(vma)); } + spin_unlock(ptl); return 0; } #else -- 2.43.0
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