From b06bad17c7435b600a1d7a35b56eff25e1d3dbc0 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 28 Apr 2016 16:18:41 -0700 Subject: [PATCH] mm: call swap_slot_free_notify() with page lock held Kyeongdon reported below error which is BUG_ON(!PageSwapCache(page)) in page_swap_info. The reason is that page_endio in rw_page unlocks the page if read I/O is completed so we need to hold a PG_lock again to check PageSwapCache. Otherwise, the page can be removed from swapcache. Kernel BUG at c00f9040 [verbose debug info unavailable] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM Modules linked in: CPU: 4 PID: 13446 Comm: RenderThread Tainted: G W 3.10.84-g9f14aec-dirty #73 task: c3b73200 ti: dd192000 task.ti: dd192000 PC is at page_swap_info+0x10/0x2c LR is at swap_slot_free_notify+0x18/0x6c pc : [] lr : [] psr: 400f0113 sp : dd193d78 ip : c2deb1e4 fp : da015180 r10: 00000000 r9 : 000200da r8 : c120fe08 r7 : 00000000 r6 : 00000000 r5 : c249a6c0 r4 : = c249a6c0 r3 : 00000000 r2 : 40080009 r1 : 200f0113 r0 : = c249a6c0 .. .. Call Trace: page_swap_info+0x10/0x2c swap_slot_free_notify+0x18/0x6c swap_readpage+0x90/0x11c read_swap_cache_async+0x134/0x1ac swapin_readahead+0x70/0xb0 handle_pte_fault+0x320/0x6fc handle_mm_fault+0xc0/0xf0 do_page_fault+0x11c/0x36c do_DataAbort+0x34/0x118 Fixes: 3f2b1a04f44933f2 ("zram: revive swap_slot_free_notify") Signed-off-by: Minchan Kim Tested-by: Kyeongdon Kim Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_io.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/page_io.c b/mm/page_io.c index cd92e3d67a3220..985f23cfa79b75 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -353,7 +353,11 @@ int swap_readpage(struct page *page) ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); if (!ret) { - swap_slot_free_notify(page); + if (trylock_page(page)) { + swap_slot_free_notify(page); + unlock_page(page); + } + count_vm_event(PSWPIN); return 0; }