From: Zi Yan <ziy@nvidia.com>
To: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Cc: usamaarif642@gmail.com, baohua@kernel.org,
cerasuolodomenico@gmail.com, corbet@lwn.net, david@redhat.com,
hannes@cmpxchg.org, kernel-team@meta.com,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
npache@redhat.com, riel@surriel.com, roman.gushchin@linux.dev,
rppt@kernel.org, ryan.roberts@arm.com, ryncsn@gmail.com,
shakeel.butt@linux.dev, willy@infradead.org, yuzhao@google.com,
Zi Yan <ziy@nvidia.com>
Subject: [PATCH] mm: avoid VM_BUG_ON when try to map an anon large folio to zero page.
Date: Wed, 23 Oct 2024 13:12:36 -0400 [thread overview]
Message-ID: <20241023171236.1122535-1-ziy@nvidia.com> (raw)
An anonymous large folio can be split into non order-0 folios,
try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but
just return false. This fixes the crash when splitting anonymous large
folios to non order-0 folios.
Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/migrate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index e950fd62607f..7ffdbe078aa7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -206,7 +206,8 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
pte_t newpte;
void *addr;
- VM_BUG_ON_PAGE(PageCompound(page), page);
+ if (PageCompound(page))
+ return false;
VM_BUG_ON_PAGE(!PageAnon(page), page);
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
--
2.45.2
next reply other threads:[~2024-10-23 17:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-23 17:12 Zi Yan [this message]
2024-10-23 18:50 ` David Hildenbrand
2024-10-23 19:59 ` Usama Arif
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