Ticket #2256 (new defect)

Opened 4 years ago

Last modified 4 years ago

[kernel] problem with swap file on fat partition

Reported by: Richard.Kralovic Owned by: openmoko-devel
Priority: normal Milestone:
Component: unknown Version:
Severity: normal Keywords:
Cc: Blocked By:
Blocking: Estimated Completion (week):
HasPatchForReview: no PatchReviewResult:
Reproducible:

Description

I tried to setup a swap file on a fat partition on sd card (using kernel linux-openmoko-2.6.28-2.6.28-oe1+git~c06ae36180dee695aa25bbae869b2aa26-r3), but the swapon command hangs; /proc/<pid>/wchan says that it hangs in _fat_bmap.

In fs/fat/inode.c:205, there is some mutex_lock protecting call to generic_block_bmap. After commenting it out, everything works nicely. But I assume this is not the correct fix...

Change History

comment:1 Changed 4 years ago by andy

Doesn't sounds like it's down to anything we're doing to the kernel in particular.

If you want to probe deeper what's happening, there are a bunch of mutex deadlock debugging CONFIG options that you should enable, it can detect deadlocks and dump the "call stack" of who holds what -- that'll shine more light on the exact source of the madness.

comment:2 Changed 4 years ago by Richard.Kralovic

Sure, I guess that it's an upstream problem. I was just wondering if there is anybody knowing about why exactly is the mutex needed. Anyway, commenting it out works around the problem, so maybe somebody finds it helpful...

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