diff mbox series

[07/13] ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()"

Message ID 20210515002722.gaOMpxsKF%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [01/13] mm/hugetlb: fix F_SEAL_FUTURE_WRITE | expand

Commit Message

Andrew Morton May 15, 2021, 12:27 a.m. UTC 
From: Hugh Dickins <hughd@google.com>
Subject: ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()"

This reverts commit 3e96b6a2e9ad929a3230a22f4d64a74671a0720b.  General
Protection Fault in rmap_walk_ksm() under memory pressure:
remove_rmap_item_from_tree() needs to take page lock, of course.

Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2105092253500.1127@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/ksm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

--- a/mm/ksm.c~ksm-revert-use-get_ksm_page_nolock-to-get-ksm-page-in-remove_rmap_item_from_tree
+++ a/mm/ksm.c
@@ -776,11 +776,12 @@  static void remove_rmap_item_from_tree(s
 		struct page *page;
 
 		stable_node = rmap_item->head;
-		page = get_ksm_page(stable_node, GET_KSM_PAGE_NOLOCK);
+		page = get_ksm_page(stable_node, GET_KSM_PAGE_LOCK);
 		if (!page)
 			goto out;
 
 		hlist_del(&rmap_item->hlist);
+		unlock_page(page);
 		put_page(page);
 
 		if (!hlist_empty(&stable_node->hlist))