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| author | Kevin Hao <haokexin@gmail.com> | 2019-11-05 21:16:57 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-12 19:15:43 +0100 |
| commit | 1bb77722ad2a9ad419066c4a724b77d0ca59b9f4 (patch) | |
| tree | d46575d0f3592a42e33ccfec4a389556d78a3974 /tools | |
| parent | ba0520468be556ae1c574c5092cea65c2938a76d (diff) | |
dump_stack: avoid the livelock of the dump_lock
commit 5cbf2fff3bba8d3c6a4d47c1754de1cf57e2b01f upstream.
In the current code, we use the atomic_cmpxchg() to serialize the output
of the dump_stack(), but this implementation suffers the thundering herd
problem. We have observed such kind of livelock on a Marvell cn96xx
board(24 cpus) when heavily using the dump_stack() in a kprobe handler.
Actually we can let the competitors to wait for the releasing of the
lock before jumping to atomic_cmpxchg(). This will definitely mitigate
the thundering herd problem. Thanks Linus for the suggestion.
[akpm@linux-foundation.org: fix comment]
Link: http://lkml.kernel.org/r/20191030031637.6025-1-haokexin@gmail.com
Fixes: b58d977432c8 ("dump_stack: serialize the output from dump_stack()")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools')
0 files changed, 0 insertions, 0 deletions