On 05/10/2012 05:45 PM, Bernd Schubert wrote: > Hi all, > > I'm just playing with an SRP connected NetApp system and just got an XFS > related kernel panic. I guess it is due to large IO (32MiB). At least it > just came up after enabling 32MiB device max_sectors. > As the tests are running in a RHEL6 image and as I needed at least > 2.6.39 to get a large srp_tablsize with SRP, I simply installed the > lasted oracle uek kernel. If needed I'm going to update to a vanilla > version. > > >> May 10 17:31:49 sgi01 kernel: XFS (sdb): Mounting Filesystem >> May 10 17:31:49 sgi01 kernel: XFS (sdb): Ending clean mount >> May 10 17:33:00 sgi01 kernel: BUG: unable to handle kernel NULL >> pointer dereference at (null) >> May 10 17:33:00 sgi01 kernel: IP: [<ffffffffa07f5483>] >> xfs_alloc_ioend_bio+0x33/0x50 [xfs] Oh, there is a bio allocation path to return NULL: bvec_alloc_bs(gfp_mask, nr_iovecs, ) => NULL when nr_iovecs > BIO_MAX_PAGES bio_alloc_bioset(gfp_mask, nr_iovecs, ...) bio_alloc(GFP_NOIO, nvecs) xfs_alloc_ioend_bio() And nvecs/nr_iovecs is obtained by bio_get_nr_vecs(), which does not check for BIO_MAX_PAGES. Of course, all of that only happens with large IO sizes, which is exactly what I'm doing. As xfs_alloc_ioend_bio() is using GFP_NOIO it does not expect bio_alloc to fail, but as I'm trying to send large IOs I guess that is exactly what happens here. >May 10 17:33:00 sgi01 kernel: [<ffffffffa07f561e>] xfs_submit_ioend+0xfe/0x110 [xfs] >May 10 17:33:00 sgi01 kernel: [<ffffffffa07f696b>] xfs_vm_writepage+0x26b/0x510 [xfs] >May 10 17:33:00 sgi01 kernel: [<ffffffff81112377>] __writepage+0x17/0x40 >May 10 17:33:00 sgi01 kernel: [<ffffffff81113696>] write_cache_pages+0x246/0x520 >May 10 17:33:00 sgi01 kernel: [<ffffffff81112360>] ? set_page_dirty+0x70/0x70 >May 10 17:33:00 sgi01 kernel: [<ffffffff811139c1>] generic_writepages+0x51/0x80 >May 10 17:33:00 sgi01 kernel: [<ffffffffa07f537d>] xfs_vm_writepages+0x5d/0x80 [xfs] >May 10 17:33:00 sgi01 kernel: [<ffffffff81113a11>] do_writepages+0x21/0x40 >May 10 17:33:00 sgi01 kernel: [<ffffffff8118df2e>] writeback_single_inode+0x10e/0x270 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
