From: Yang Shi <yang.shi@linux.alibaba.com> To: kirill.shutemov@linux.intel.com, akpm@linux-foundation.org Cc: gavin.dg@linux.alibaba.com, yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one() Date: Tue, 6 Feb 2018 08:06:36 +0800 [thread overview] Message-ID: <1517875596-76350-1-git-send-email-yang.shi@linux.alibaba.com> (raw) For PTE-mapped THP, the compound THP has not been split to normal 4K pages yet, the whole THP is considered referenced if any one of sub page is referenced. When walking PTE-mapped THP by pvmw, all relevant PTEs will be checked to retrieve referenced bit. But, the current code just returns the result of the last PTE. If the last PTE has not referenced, the referenced flag will be cleared. So, here just break pvmw walk once referenced PTE is found if the page is a part of THP. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reported-by: Gang Deng <gavin.dg@linux.alibaba.com> --- mm/page_idle.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/page_idle.c b/mm/page_idle.c index 0a49374..da6024f 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -67,6 +67,14 @@ static bool page_idle_clear_pte_refs_one(struct page *page, if (pvmw.pte) { referenced = ptep_clear_young_notify(vma, addr, pvmw.pte); + /* + * For PTE-mapped THP, one sub page is referenced, + * the whole THP is referenced. + */ + if (referenced && PageTransCompound(pvmw.page)) { + page_vma_mapped_walk_done(&pvmw); + break; + } } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { referenced = pmdp_clear_young_notify(vma, addr, pvmw.pmd); -- 1.8.3.1
WARNING: multiple messages have this Message-ID (diff)
From: Yang Shi <yang.shi@linux.alibaba.com> To: kirill.shutemov@linux.intel.com, akpm@linux-foundation.org Cc: gavin.dg@linux.alibaba.com, yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one() Date: Tue, 6 Feb 2018 08:06:36 +0800 [thread overview] Message-ID: <1517875596-76350-1-git-send-email-yang.shi@linux.alibaba.com> (raw) For PTE-mapped THP, the compound THP has not been split to normal 4K pages yet, the whole THP is considered referenced if any one of sub page is referenced. When walking PTE-mapped THP by pvmw, all relevant PTEs will be checked to retrieve referenced bit. But, the current code just returns the result of the last PTE. If the last PTE has not referenced, the referenced flag will be cleared. So, here just break pvmw walk once referenced PTE is found if the page is a part of THP. Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reported-by: Gang Deng <gavin.dg@linux.alibaba.com> --- mm/page_idle.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/page_idle.c b/mm/page_idle.c index 0a49374..da6024f 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -67,6 +67,14 @@ static bool page_idle_clear_pte_refs_one(struct page *page, if (pvmw.pte) { referenced = ptep_clear_young_notify(vma, addr, pvmw.pte); + /* + * For PTE-mapped THP, one sub page is referenced, + * the whole THP is referenced. + */ + if (referenced && PageTransCompound(pvmw.page)) { + page_vma_mapped_walk_done(&pvmw); + break; + } } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { referenced = pmdp_clear_young_notify(vma, addr, pvmw.pmd); -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next reply other threads:[~2018-02-06 0:07 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-06 0:06 Yang Shi [this message] 2018-02-06 0:06 ` [PATCH] mm: thp: fix potential clearing to referenced flag in page_idle_clear_pte_refs_one() Yang Shi 2018-02-08 22:39 ` Andrew Morton 2018-02-08 22:39 ` Andrew Morton 2018-02-09 4:33 ` Kirill A. Shutemov 2018-02-09 4:33 ` Kirill A. Shutemov 2018-02-09 4:47 ` Yang Shi 2018-02-09 4:47 ` Yang Shi 2018-02-09 8:16 ` Kirill A. Shutemov 2018-02-09 8:16 ` Kirill A. Shutemov 2018-02-09 19:14 ` Yang Shi 2018-02-09 19:14 ` Yang Shi
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