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From: Hugh Dickins <hughd@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org,  linux-mm@kvack.org
Subject: [PATCH next] mm/migrate: fix remove_migration_pte() of hugetlb entry
Date: Sat, 26 Feb 2022 18:25:15 -0800 (PST)	[thread overview]
Message-ID: <bd28ebcf-4d42-7184-8189-ffed6fe7d4dc@google.com> (raw)

The foliation of remove_migration_pte() is currently wrong on hugetlb
anon entries, causing LTP move_pages12 to crash on BUG_ON(!PageLocked)
in hugepage_add_anon_rmap().

Fixes: b4010e88f071 ("mm/migrate: Convert remove_migration_ptes() to folios")
Signed-off-by: Hugh Dickins <hughd@google.com>
---
Please just fold in if you agree.

 mm/migrate.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- mmotm/mm/migrate.c
+++ linux/mm/migrate.c
@@ -182,7 +182,8 @@ static bool remove_migration_pte(struct
 		struct page *new;
 		unsigned long idx = 0;
 
-		if (!folio_test_ksm(folio))
+		/* Skip call in common case, plus .pgoff is invalid for KSM */
+		if (pvmw.nr_pages != 1 && !folio_test_hugetlb(folio))
 			idx = linear_page_index(vma, pvmw.address) - pvmw.pgoff;
 		new = folio_page(folio, idx);
 


             reply	other threads:[~2022-02-27  2:25 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-27  2:25 Hugh Dickins [this message]
2022-02-28 20:49 ` Matthew Wilcox
2022-02-28 22:18   ` Hugh Dickins

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