4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Yisheng Xie <[email protected]> [ 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/[email protected] Signed-off-by: Yisheng Xie <[email protected]> Suggested-by: Catalin Marinas <[email protected]> Acked-by: Catalin Marinas <[email protected]> Cc: Michal Hocko <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -1394,6 +1394,8 @@ 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();
