Fix for recent bugzilla reports related to long halts during block allocation
Status from this message: Applied, thanks!
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Patches in v1 Applied
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/1 | ext4: fallback to complex scan if aligned scan doesn't workfs/ | +13 | 2 replies |
Reviews trailers per patch
The patch has a Reviewed-by or Acked-by.
| Patch | Jan Kara |
|---|---|
| 1/1 | R-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/1] Fix for recent bugzilla reports related to long halts during block allocation
This patch intends to fix the recent bugzilla [1] report where the kworker flush thread seemed to be taking 100% CPU utilizationa and was slowing down the whole system. The backtrace indicated that we were stuck in mballoc allocation path. The issue was only seen kernel 6.5+ and when ext4 was mounted with -o stripe (or stripe option was implicitly added due us mkfs flags used).
Although I was not able to fully replicate this issue, from the perf probe logs collected I have a possible root cause which I have explained in the patch commit message.
Now, the one thing I'm still skeptical about is why this was only seen in kernel 6.5+. We added a new mballoc criteria in kernel 6.5 but I was not able to find a satisfactory explanation as to why that would have any effect here. Furter, the issue still persisted when I asked one of the reporters to disable the it using sysfs file and rerun the test. Maybe there are some more factors at play?
Anyways, I would appreciate if the people experiencing this issue can help test this patch and see if it fixes the regression.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=217965
Regards,
ojaswin
Ojaswin Mujoo (1):
ext4: fallback to complex scan if aligned scan doesn't work
fs/ext4/mballoc.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
Signature · 1 line
2.39.3