From: Rafael Aquini Date: Mon, 30 Sep 2013 20:45:16 +0000 (-0700) Subject: mm: avoid reinserting isolated balloon pages into LRU lists X-Git-Tag: v3.12-rc4~35^2~9 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=117aad1e9e4d97448d1df3f84b08bd65811e6d6a;p=karo-tx-linux.git mm: avoid reinserting isolated balloon pages into LRU lists Isolated balloon pages can wrongly end up in LRU lists when migrate_pages() finishes its round without draining all the isolated page list. The same issue can happen when reclaim_clean_pages_from_list() tries to reclaim pages from an isolated page list, before migration, in the CMA path. Such balloon page leak opens a race window against LRU lists shrinkers that leads us to the following kernel panic: BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 IP: [] shrink_page_list+0x24e/0x897 PGD 3cda2067 PUD 3d713067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 340 Comm: kswapd0 Not tainted 3.12.0-rc1-22626-g4367597 #87 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: shrink_page_list+0x24e/0x897 RSP: 0000:ffff88003da499b8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88003e82bd60 RCX: 00000000000657d5 RDX: 0000000000000000 RSI: 000000000000031f RDI: ffff88003e82bd40 RBP: ffff88003da49ab0 R08: 0000000000000001 R09: 0000000081121a45 R10: ffffffff81121a45 R11: ffff88003c4a9a28 R12: ffff88003e82bd40 R13: ffff88003da0e800 R14: 0000000000000001 R15: ffff88003da49d58 FS: 0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000067d9000 CR3: 000000003ace5000 CR4: 00000000000407b0 Call Trace: shrink_inactive_list+0x240/0x3de shrink_lruvec+0x3e0/0x566 __shrink_zone+0x94/0x178 shrink_zone+0x3a/0x82 balance_pgdat+0x32a/0x4c2 kswapd+0x2f0/0x372 kthread+0xa2/0xaa ret_from_fork+0x7c/0xb0 Code: 80 7d 8f 01 48 83 95 68 ff ff ff 00 4c 89 e7 e8 5a 7b 00 00 48 85 c0 49 89 c5 75 08 80 7d 8f 00 74 3e eb 31 48 8b 80 18 01 00 00 <48> 8b 74 0d 48 8b 78 30 be 02 00 00 00 ff d2 eb RIP [] shrink_page_list+0x24e/0x897 RSP CR2: 0000000000000028 ---[ end trace 703d2451af6ffbfd ]--- Kernel panic - not syncing: Fatal exception This patch fixes the issue, by assuring the proper tests are made at putback_movable_pages() & reclaim_clean_pages_from_list() to avoid isolated balloon pages being wrongly reinserted in LRU lists. [akpm@linux-foundation.org: clarify awkward comment text] Signed-off-by: Rafael Aquini Reported-by: Luiz Capitulino Tested-by: Luiz Capitulino Cc: Mel Gorman Cc: Rik van Riel Cc: Hugh Dickins Cc: Johannes Weiner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h index f7f1d7169b11..089743ade734 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -158,6 +158,26 @@ static inline bool balloon_page_movable(struct page *page) return false; } +/* + * isolated_balloon_page - identify an isolated balloon page on private + * compaction/migration page lists. + * + * After a compaction thread isolates a balloon page for migration, it raises + * the page refcount to prevent concurrent compaction threads from re-isolating + * the same page. For that reason putback_movable_pages(), or other routines + * that need to identify isolated balloon pages on private pagelists, cannot + * rely on balloon_page_movable() to accomplish the task. + */ +static inline bool isolated_balloon_page(struct page *page) +{ + /* Already isolated balloon pages, by default, have a raised refcount */ + if (page_flags_cleared(page) && !page_mapped(page) && + page_count(page) >= 2) + return __is_movable_balloon_page(page); + + return false; +} + /* * balloon_page_insert - insert a page into the balloon's page list and make * the page->mapping assignment accordingly. @@ -243,6 +263,11 @@ static inline bool balloon_page_movable(struct page *page) return false; } +static inline bool isolated_balloon_page(struct page *page) +{ + return false; +} + static inline bool balloon_page_isolate(struct page *page) { return false; diff --git a/mm/migrate.c b/mm/migrate.c index 9c8d5f59d30b..a26bccd44ccb 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -107,7 +107,7 @@ void putback_movable_pages(struct list_head *l) list_del(&page->lru); dec_zone_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); - if (unlikely(balloon_page_movable(page))) + if (unlikely(isolated_balloon_page(page))) balloon_page_putback(page); else putback_lru_page(page); diff --git a/mm/vmscan.c b/mm/vmscan.c index beb35778c69f..53f2f82f83ae 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -48,6 +48,7 @@ #include #include +#include #include "internal.h" @@ -1113,7 +1114,8 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, LIST_HEAD(clean_pages); list_for_each_entry_safe(page, next, page_list, lru) { - if (page_is_file_cache(page) && !PageDirty(page)) { + if (page_is_file_cache(page) && !PageDirty(page) && + !isolated_balloon_page(page)) { ClearPageActive(page); list_move(&page->lru, &clean_pages); }