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| author | Rik van Riel <riel@surriel.com> | 2025-01-10 10:28:21 -0500 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-01-12 19:03:38 -0800 |
| commit | cbc5dde0a461240046e8a41c43d7c3b76d5db952 (patch) | |
| tree | 234a069ca24ea1ea3efdb3b5ea16afba711b88bd | |
| parent | 1c47c57818ad73d2d09ddbcb4839708aab5ff2e3 (diff) | |
| download | lwn-cbc5dde0a461240046e8a41c43d7c3b76d5db952.tar.gz lwn-cbc5dde0a461240046e8a41c43d7c3b76d5db952.zip | |
fs/proc: fix softlockup in __read_vmcore (part 2)
Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the
number of softlockups in __read_vmcore at kdump time have gone down, but
they still happen sometimes.
In a memory constrained environment like the kdump image, a softlockup is
not just a harmless message, but it can interfere with things like RCU
freeing memory, causing the crashdump to get stuck.
The second loop in __read_vmcore has a lot more opportunities for natural
sleep points, like scheduling out while waiting for a data write to
happen, but apparently that is not always enough.
Add a cond_resched() to the second loop in __read_vmcore to (hopefully)
get rid of the softlockups.
Link: https://lkml.kernel.org/r/20250110102821.2a37581b@fangorn
Fixes: 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore")
Signed-off-by: Rik van Riel <riel@surriel.com>
Reported-by: Breno Leitao <leitao@debian.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/proc/vmcore.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index 3d8a82cee63e..658bf199d424 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -404,6 +404,8 @@ static ssize_t __read_vmcore(struct iov_iter *iter, loff_t *fpos) if (!iov_iter_count(iter)) return acc; } + + cond_resched(); } return acc; |