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? -Sandeep -- 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
