From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: [PATCH] shrink_list skip anon pages if not may_swap From: Lee Schermerhorn Reply-To: lee.schermerhorn@hp.com Content-Type: text/plain Date: Mon, 12 Sep 2005 13:29:51 -0400 Message-Id: <1126546191.5182.29.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm Cc: Martin Hicks , lhms-devel List-ID: Martin Hicks' page cache reclaim patch added the 'may_swap' flag to the scan_control struct; and modified shrink_list() not to add anon pages to the swap cache if may_swap is not asserted. Ref: http://marc.theaimsgroup.com/?l=linux-mm&m=111461480725322&w=4 However, further down, if the page is mapped, shrink_list() calls try_to_unmap() which will call try_to_unmap_one() via try_to_unmap_anon (). try_to_unmap_one() will BUG_ON() an anon page that is NOT in the swap cache. Martin says he never encountered this path in his testing, but agrees that it might happen. This patch modifies shrink_list() to skip anon pages that are not already in the swap cache when !may_swap, rather than just not adding them to the cache. Cc to lhms-devel because memory hotplug page migration also uses shrink_list. Signed-off-by: Lee Schermerhorn ============================================================ --- shrink_list-skip-anon-pages-if-not-may_swap/mm/vmscan.c~original 2005-08-28 19:41:01.000000000 -0400 +++ shrink_list-skip-anon-pages-if-not-may_swap/mm/vmscan.c 2005-09-12 10:17:01.000000000 -0400 @@ -417,7 +417,9 @@ static int shrink_list(struct list_head * Anonymous process memory has backing store? * Try to allocate it some swap space here. */ - if (PageAnon(page) && !PageSwapCache(page) && sc->may_swap) { + if (PageAnon(page) && !PageSwapCache(page)) { + if (!sc->may_swap) + goto keep_locked; if (!add_to_swap(page)) goto activate_locked; } -- 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: email@kvack.org