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authorMinchan Kim <minchan@kernel.org>2016-04-28 16:18:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-04-28 19:34:04 -0700
commitb06bad17c7435b600a1d7a35b56eff25e1d3dbc0 (patch)
treeb75e803dfc71fb95ec67cba0cc17876ca48942f9
parent7bf52fb891b64b8d61caf0b82060adb9db761aec (diff)
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 : [<c00f9040>] lr : [<c00f5560>] 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 ..<snip> .. 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 <minchan@kernel.org> Tested-by: Kyeongdon Kim <kyeongdon.kim@lge.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_io.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/page_io.c b/mm/page_io.c
index cd92e3d67a32..985f23cfa79b 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;
}