linux-kernel - [PATCH AUTOSEL for 4.9 39/55] kmemleak: add scheduling point to kmemleak

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Message-ID: <20180124041521.32223-39-alexander.levin@microsoft.com>
Date:   Wed, 24 Jan 2018 04:15:49 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Yisheng Xie <xieyisheng1@...wei.com>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 39/55] kmemleak: add scheduling point to
 kmemleak_scan()

From: Yisheng Xie <xieyisheng1@...wei.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@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
Suggested-by: Catalin Marinas <catalin.marinas@....com>
Acked-by: Catalin Marinas <catalin.marinas@....com>
Cc: Michal Hocko <mhocko@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 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