On Thu, 2013-09-05 at 05:35 +0900, Ryusuke Konishi wrote: > Usually pages in nilfs are not marked dirty while the log writer is > writing. ns_segctor_sem is used for this exclusion control. > > But, we have an exception -- nilfs_set_page_dirty(). > > I now suspect the root cause is that nilfs_set_page_dirty() can > asynchronously mark pages dirty on mmapped files. > > Can you confirm this assumption by comparing addresses of the > following two page structures ? > > 1. Address of page structures passed to nilfs_set_page_dirty(). > 2. bh->b_page of the buffer head captured by the above BUG_ON checks. > So, I have such output in my syslog: [ 257.825054] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 257.825072] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 257.855659] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 258.115918] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 258.622433] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 258.622433] NILFS [nilfs_set_page_dirty]:225 page ffffea000687d680 [ 258.643247] NILFS [nilfs_lookup_dirty_data_buffers]:673 bh->b_page ffffea000687d680, bh->b_blocknr 0 [ 258.643290] ------------[ cut here ]------------ [ 258.643294] kernel BUG at fs/nilfs2/segment.c:676! And I can see such call trace for the case of nilfs_set_page_dirty() call: [ 441.538563] Call Trace: [ 441.538568] [<ffffffff816df345>] dump_stack+0x19/0x1b [ 441.538574] [<ffffffff812ae1cc>] nilfs_set_page_dirty+0x1c/0xa0 [ 441.538579] [<ffffffff8112e75e>] set_page_dirty+0x3e/0x60 [ 441.538584] [<ffffffff8112e838>] clear_page_dirty_for_io+0xb8/0xc0 [ 441.538589] [<ffffffff812c01d9>] nilfs_begin_page_io.part.24+0x29/0x50 [ 441.538595] [<ffffffff812c0e6c>] nilfs_segctor_do_construct+0xc6c/0x1ba0 [ 441.538601] [<ffffffff812c20b3>] nilfs_segctor_construct+0x183/0x2a0 [ 441.538607] [<ffffffff812c2316>] nilfs_segctor_thread+0x146/0x370 [ 441.538613] [<ffffffff812c21d0>] ? nilfs_segctor_construct+0x2a0/0x2a0 [ 441.538617] [<ffffffff8106bc9d>] kthread+0xed/0x100 [ 441.538623] [<ffffffff8106bbb0>] ? flush_kthread_worker+0x190/0x190 [ 441.538628] [<ffffffff816ef35c>] ret_from_fork+0x7c/0xb0 [ 441.538633] [<ffffffff8106bbb0>] ? flush_kthread_worker+0x190/0x190 So, as I understand, segctor thread calls nilfs_set_page_dirty() on the segment construction phase by itself. Today I haven't more time for analyzing it in details. I hope that this output will be useful for you. I'll analyze it more deeply tomorrow. And if you need in additional details, please, feel free to ask me. With the best regards, Vyacheslav Dubeyko. -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
