On Sun, Jun 06, 2010 at 01:59:47PM +0200, Markus Trippelsdorf wrote: > On Sun, Jun 06, 2010 at 07:45:48AM -0400, Theodore Tso wrote: > > > > On Jun 6, 2010, at 4:16 AM, Markus Trippelsdorf wrote: > > > > > Commit 1f5a81e41f8b1a782c68d3843e9ec1bfaadf7d72 > > > "ext4: Make sure the MOVE_EXT ioctl can't overwrite append-only files" > > > causes the following kernel BUG on my machine (x86_64): > > > > > > BUG: Bad page map in process mpd pte:720072000000000 pmd:11d2f7067 > > > addr:00007f6b09f82000 vm_flags:08000070 anon_vma:(null) mapping:ffff88011b1cec18 index:132 > > > vma->vm_ops->fault: filemap_fault+0x0/0x31e > > > vma->vm_file->f_op->mmap: ext4_file_mmap+0x0/0x54 > > > Pid: 1672, comm: mpd Not tainted 2.6.35-rc2-00032-g78a5aa2 #45 > > > Call Trace: > > > [<ffffffff810b7a35>] print_bad_pte+0x1d0/0x1e9 > > > [<ffffffff810b8c9b>] unmap_vmas+0x50c/0x803 > > > [<ffffffff810be003>] exit_mmap+0xc4/0x14a > > > [<ffffffff81057bc6>] mmput+0x2d/0xb9 > > > > What makes you think it was the commit you cited that is causing this crash? Unless you are specifically using e2defrag (or write code which explicitly calls this ext4-specific ioctl), the code path in question wouldn't even be entered, and I see nothing in this stack trace to indicate it was caused by this change. > > > > (And in fact in a subsequent e-mail I see that you've tried reverting both changes to ext4 between rc1 and rc2 and it didn't seem to help.) > > > > Have you tried bisecting the kernel to find commit which introduced this problem? What was the last kernel that didn't have these problem for you? -rc1? How easy is this to reproduce? Does this happen as soon as you boot up your system? > > > I did a git pull this morning and hit the problem after rebooting. I > then looked in the changelog for recent ext4 commits and found the two > entries. I reverted the first one and the problem was still there. > Then I reverted the second one and the problem went away. After that I > reverted my last revert and the problem reappeared... > > (From that I concluded that 1f5a81e41f8b1a782c68d3843e9ec1bfaadf7d72 was > the root of the problem. But maybe it was just a strange coincident) > > I haven't tried a full bisection yet. The last working kernel was just > the git kernel from about 5 days ago. The bug is quiet easy to reproduce > and usually happens right after I boot my system and sometimes when I > shut it down. > > I will try a bisection later today. Since this bug is not deterministically reproducible bisecting turned out harder then anticipated. I get as far as: bad d2dd328b7f7bc6cebe167648289337755944ad2a good a094c0afc3515aaf962dd0793f3b23fe67e6b192 (Take even this result with a grain of salt, because a single wrong "git bisect good" will lead to wrong results) After that git bisect quickly goes to lala land. -- Markus -- 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
