On Wed, Oct 23, 2013 at 08:28:22PM +0530, Sandeep Joshi wrote: > On Wed, Oct 23, 2013 at 3:50 PM, Jan Kara <jack@xxxxxxx> wrote: > > On Mon 21-10-13 18:09:02, Sandeep Joshi wrote: > >> I am seeing a problem reported 4 years earlier > >> https://lkml.org/lkml/2009/3/12/226 > >> (same stack as seen by Alexander) > >> > >> The problem is reproducible. Let me know if you need any info in > >> addition to that seen below. > >> > >> I have multiple threads in a process doing heavy IO on a ext4 > >> filesystem mounted with (discard, noatime) on a SSD or HDD. > >> > >> This is on Linux 3.8.0-29-generic #42~precise1-Ubuntu SMP Wed Aug 14 > >> 16:19:23 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux > >> > >> For upto minutes at a time, one of the threads seems to hang in sync to disk. > >> > >> When I check the thread stack in /proc, I find that the stack is one > >> of the following two > >> > >> <ffffffff81134a4e>] sleep_on_page+0xe/0x20 > >> [<ffffffff81134c88>] wait_on_page_bit+0x78/0x80 > >> [<ffffffff81134d9c>] filemap_fdatawait_range+0x10c/0x1a0 > >> [<ffffffff811367d8>] filemap_write_and_wait_range+0x68/0x80 > >> [<ffffffff81236a4f>] ext4_sync_file+0x6f/0x2b0 > >> [<ffffffff811cba9b>] vfs_fsync+0x2b/0x40 > >> [<ffffffff81168fb3>] sys_msync+0x143/0x1d0 > >> [<ffffffff816fc8dd>] system_call_fastpath+0x1a/0x1f > >> [<ffffffffffffffff>] 0xffffffffffffffff > >> > >> > >> OR > >> > >> > >> [<ffffffff812947f5>] jbd2_log_wait_commit+0xb5/0x130 > >> [<ffffffff81297213>] jbd2_complete_transaction+0x53/0x90 > >> [<ffffffff81236bcd>] ext4_sync_file+0x1ed/0x2b0 > >> [<ffffffff811cba9b>] vfs_fsync+0x2b/0x40 > >> [<ffffffff81168fb3>] sys_msync+0x143/0x1d0 > >> [<ffffffff816fc8dd>] system_call_fastpath+0x1a/0x1f > >> [<ffffffffffffffff>] 0xffffffffffffffff > >> > >> Any clues? > > We are waiting for IO to complete. As the first thing, try to remount > > your filesystem without 'discard' mount option. That is often causing > > problems. > > > > Honza > > > Thanks Jan, I will remove it and see what happens. > I was also planning to switch to ext2 and see if the failure continues. > I added the discard option because the filesystem was initially > supposed to be on an SSD > > is there any document which tells me what to look for in the output of > "echo w > /proc/sysrq-trigger" ? Sorry for the late. Here it is [1]. I want to look at which process is blocked. Please try the testing as Jan suggested. 1. http://lxr.free-electrons.com/source/Documentation/sysrq.txt Regards, - Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
