4.9-stable review patch. If anyone has any objections, please let me know.
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From: Yisheng Xie xieyisheng1@huawei.com
[ 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@huawe... Signed-off-by: Yisheng Xie xieyisheng1@huawei.com Suggested-by: Catalin Marinas catalin.marinas@arm.com Acked-by: Catalin Marinas catalin.marinas@arm.com Cc: Michal Hocko mhocko@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+)
--- 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();