Messages in this thread | | | Date | Mon, 17 Dec 2007 18:52:13 -0800 | From | Andrew Morton <> | Subject | Re: 2.6.24-rc5-mm1 - wonky disk cache and CDROM behavior... |
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On Tue, 18 Dec 2007 10:37:32 +0800 Dave Young <hidave.darkstar@gmail.com> wrote:
> On Mon, Dec 17, 2007 at 09:07:56PM -0500, Valdis.Kletnieks@vt.edu wrote: > > On Mon, 17 Dec 2007 14:56:44 PST, Andrew Morton said: > > > > (Adding Al Viro to the list, he's listed as "file systems" and MAINTAINERS > > doesn't list 'isofs' anyplace. Will Al or Andrew please vector to whoever > > actually does that code?) > > > > > > I try it again, and it reports it died at the same exact place, but in about > > > > 2 seconds flat, and reports 91M/sec transfer. OK, that's *weird*, I didn't > > > > think that blocks read from /dev/cdrom would get cached, but OK. > > > > > > It'll remain cached if something is holding the device open. > > > > Does it need to be "device open", or are there other things as well? If the > > drop_cache was hosed, that would result in the same symptoms, no? > > > > > Something's holding s_umount for writing I guess. Possibly busted error > > > handling somewhere totally different. > > > > Aha - found what was holding it - an attempt to loopback mount the truncated > > file (before I realized it was truncated) had failed - I had gotten a 'Killed' > > back from the mount, but I didn't realize it had pulled an actual oops: > > > > Dec 17 15:54:33 turing-police kernel: [14503.402385] attempt to access beyond end of device > > Dec 17 15:54:33 turing-police kernel: [14503.402391] loop1: rw=0, want=1284500, limit=314240 > > Dec 17 15:54:33 turing-police kernel: [14503.402395] ISOFS: unable to read i-node block > > Dec 17 15:54:33 turing-police kernel: [14503.402428] Unable to handle kernel NULL pointer dereference at 000000000000010b RIP: > > Dec 17 15:54:33 turing-police kernel: [14503.402440] [<ffffffff802a096b>] iput+0x11/0x80 > > ... > > Dec 17 15:54:33 turing-police kernel: [14503.403008] Call Trace: > > Dec 17 15:54:33 turing-police kernel: [14503.403026] [<ffffffff802ff73e>] isofs_fill_super+0x7e9/0xa6b > > Dec 17 15:54:33 turing-police kernel: [14503.403045] [<ffffffff80523d28>] __down_write_nested+0x3d/0xa1 > > Dec 17 15:54:33 turing-police kernel: [14503.403061] [<ffffffff80523d97>] __down_write+0xb/0xd > > Dec 17 15:54:33 turing-police kernel: [14503.403076] [<ffffffff8028fb63>] sget+0x397/0x3a9 > > Dec 17 15:54:33 turing-police kernel: [14503.403090] [<ffffffff8028f204>] set_bdev_super+0x0/0x14 > > Dec 17 15:54:33 turing-police kernel: [14503.403106] [<ffffffff80290301>] get_sb_bdev+0x109/0x157 > > Dec 17 15:54:33 turing-police kernel: [14503.403120] [<ffffffff802fef55>] isofs_fill_super+0x0/0xa6b > > Dec 17 15:54:33 turing-police kernel: [14503.403138] [<ffffffff802fe2e9>] isofs_get_sb+0x13/0x15 > > Dec 17 15:54:33 turing-police kernel: [14503.403151] [<ffffffff80290075>] vfs_kern_mount+0x90/0x11a > > Dec 17 15:54:33 turing-police kernel: [14503.403167] [<ffffffff8029015c>] do_kern_mount+0x47/0xe3 > > Dec 17 15:54:33 turing-police kernel: [14503.403183] [<ffffffff802a5012>] do_mount+0x717/0x78a > > Dec 17 15:54:33 turing-police kernel: [14503.403199] [<ffffffff805242fc>] _read_lock_irq+0x9/0xb > > Dec 17 15:54:33 turing-police kernel: [14503.403212] [<ffffffff8026cce0>] find_lock_page+0x8c/0x97 > > Dec 17 15:54:33 turing-police kernel: [14503.403227] [<ffffffff8026ecb6>] filemap_fault+0x1fa/0x3c6 > > Dec 17 15:54:33 turing-police kernel: [14503.403241] [<ffffffff8026cb6b>] unlock_page+0x2d/0x31 > > Dec 17 15:54:33 turing-police kernel: [14503.403254] [<ffffffff8027925c>] __do_fault+0x38d/0x3c3 > > Dec 17 15:54:33 turing-police kernel: [14503.403274] [<ffffffff8027ab68>] handle_mm_fault+0x36d/0x6e9 > > Dec 17 15:54:33 turing-police kernel: [14503.403293] [<ffffffff80271903>] __alloc_pages+0x68/0x2f6 > > Dec 17 15:54:33 turing-police kernel: [14503.403314] [<ffffffff802a510e>] sys_mount+0x89/0xcb > > Dec 17 15:54:33 turing-police kernel: [14503.403328] [<ffffffff80214f34>] syscall_trace_enter+0x97/0x9b > > Dec 17 15:54:33 turing-police kernel: [14503.403344] [<ffffffff8020c34c>] tracesys+0xdc/0xe1 > > Dec 17 15:54:33 turing-police kernel: [14503.403359] > > Dec 17 15:54:33 turing-police kernel: [14503.403366] > > Dec 17 15:54:33 turing-police kernel: [14503.403367] Code: 48 8b 87 10 01 00 00 48 83 bf 38 02 00 00 40 48 8b 40 38 75 > > > > I don't mind it failing the mount, but the oops seems excessive. I suspect > > that *somewhere* in that stack trace, we're wanting something like a > > > > if (!foo_ptr) > > return -EIO; > > > > but I admit not being competent enough to decide where that should be. > > > > Hi, > Could you please try the below patch: > > Signed-off-by: Dave Young <hidave.darkstar@gmail.com> > > --- > fs/isofs/inode.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff -upr linux/fs/isofs/inode.c linux.new/fs/isofs/inode.c > --- linux/fs/isofs/inode.c 2007-12-18 10:31:12.000000000 +0800 > +++ linux.new/fs/isofs/inode.c 2007-12-18 10:31:56.000000000 +0800 > @@ -1414,7 +1414,7 @@ struct inode *isofs_iget(struct super_bl > ret = isofs_read_inode(inode); > if (ret < 0) { > iget_failed(inode); > - inode = ERR_PTR(ret); > + return NULL; > } else { > unlock_new_inode(inode); > } >
Yup.
David, this is concerning. More such error-path bugs in that code will take years and years to get found and fixed. The best way to eliminate them is a line-by-line re-review of the patchset.
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