[PATCH AUTOSEL for 4.9 39/55] kmemleak: add scheduling point to kmemleak_scan()

From: Sasha Levin
Date: Tue Jan 23 2018 - 23:18:27 EST


From: Yisheng Xie <xieyisheng1@xxxxxxxxxx>

[ Upstream commit bde5f6bc68db51128f875a756e9082a6c6ff7b4c ]

kmemleak_scan() will scan struct page for each node and it can be really
large and resulting in a soft lockup. We have seen a soft lockup when
do scan while compile kernel:

watchdog: BUG: soft lockup - CPU#53 stuck for 22s! [bash:10287]
[...]
Call Trace:
kmemleak_scan+0x21a/0x4c0
kmemleak_write+0x312/0x350
full_proxy_write+0x5a/0xa0
__vfs_write+0x33/0x150
vfs_write+0xad/0x1a0
SyS_write+0x52/0xc0
do_syscall_64+0x61/0x1a0
entry_SYSCALL64_slow_path+0x25/0x25

Fix this by adding cond_resched every MAX_SCAN_SIZE.

Link: http://lkml.kernel.org/r/1511439788-20099-1-git-send-email-xieyisheng1@xxxxxxxxxx
Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
Suggested-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
mm/kmemleak.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index d1380ed93fdf..20cf3be9a5e8 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1442,6 +1442,8 @@ static void kmemleak_scan(void)
if (page_count(page) == 0)
continue;
scan_block(page, page + 1, NULL);
+ if (!(pfn % (MAX_SCAN_SIZE / sizeof(*page))))
+ cond_resched();
}
}
put_online_mems();
--
2.11.0