Messages in this thread Patch in this message |  | | Date | Thu, 09 Jan 2003 02:06:55 -0800 | From | Andrew Morton <> | Subject | Re: 2.4.18-14 kernel stuck during ext3 umount with ping still responding |
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yuval yeret wrote: > > Hi, > > I'm running a 2.4.18-14 kernel with a heavy IO profile using ext3 over RAID > 0+1 volumes. > > >From time to time I get a black screen stuck machine while trying to umount > a volume during an IO workload (as part of a failback solution - but after > killing all IO processes ), with ping still responding, but everything else > mostly dead. > > I tried using the forcedumount patch to solve this problem - to no avail. > Also tried upgrading the qlogic drivers to the latest drivers from Qlogic. > > After one of the occurences I managed to get some output using the sysrq > keys. > > This seems similar to what is described in > http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=77508 but with a > different call trace > > What I have here is what I managed to copy down (for some reason pgup/pgdown > didn't work so not all information is full...) together with a manual lookup > of the call trace > from /proc/ksyms : > > process umount > EIP c01190b8 (set_running_and_schedule) > call trace: > c01144c9 f25f9ec0 IO_APIC_get_PCI_irq_vector > c010a8b0 f25f9ed0 enable_irq > c014200c f25f9ef0 fsync_buffers_list > c0155595 f25f9efc clear_inode > c015553d f25f9f2c invalidate_inodes > c01461d8 f25f9f78 get_super > c014a629 f25f9f94 path_release > c0157c58 f25f9fc0 sys_umount > c0108cab sys_sigaltstack > > Any idea what can cause this ? >
If you have a large amount of data against two or more filesystems, and you try to unmount one of them the kernel can seize up for a very long time in the fsync_dev()->sync_buffers() function. Under these circumstances that function has O(n*n) search complexity and n is quite large.
However your backtrace shows neither of those functions.
Still, as an experiment it would be interesting to see if the below patch fixes it up. It converts O(n*n) to O(m), where m > n.
fs/buffer.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)
--- 2420/fs/buffer.c~a Thu Jan 9 02:03:06 2003 +++ 2420-akpm/fs/buffer.c Thu Jan 9 02:04:02 2003 @@ -307,11 +307,11 @@ int sync_buffers(kdev_t dev, int wait) * 2) write out all dirty, unlocked buffers; * 2) wait for completion by waiting for all buffers to unlock. */ - write_unlocked_buffers(dev); + write_unlocked_buffers(NODEV); if (wait) { - err = wait_for_locked_buffers(dev, BUF_DIRTY, 0); + err = wait_for_locked_buffers(NODEV, BUF_DIRTY, 0); write_unlocked_buffers(dev); - err |= wait_for_locked_buffers(dev, BUF_LOCKED, 1); + err |= wait_for_locked_buffers(NODEV, BUF_LOCKED, 1); } return err; } _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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