Commit 62862290 authored May 14, 2021 by Hugh Dickins Committed by Linus Torvalds May 14, 2021

ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()"

This reverts commit 3e96b6a2.  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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7ed9d238

mm/ksm.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -776,11 +776,12 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
		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))