On Mon, 13 May 2013 09:30:36 -0400, Theodore Ts'o <tytso@xxxxxxx> wrote: > On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote: > > Grumble. In this case I think bitfields are not worth the trouble with gcc. > > It's a pitty we have to spend additional 8 bytes for every journal_head but > > we'll survive... I'll send Ted a partial revert and add a comment so that > > we won't repeat this mistake in future. > > Or just switch things to use explicit 32-bit boolean operations. > Sounds the safest way to go is to simply not trust bitfields to be > something gcc is competent to compile correctly, and just open code it > in standard C. (Large portions of ext4 and e2fsprogs do this > manually, for historical reasons, and it sounds like we have a good > reason to do it going forward.) > > Jan, Dmitry --- I still have in my tree a revert for commit 4eec708d2: > ext4: use io_end for multiple bios, since I belive Dmitry still > bisected a regression for xfstests 299. Dmitry, can you confirm that > you are definitely seeing a regression here? Yes, this patch provoke use-after-free which detected by slab sanity checks. > Jan, do you mind if we > try to figure out how to fix this during the next development cycle, > since it was part of your much longer, extensive patch series anyway? > > I've determined that the reason why I didn't see a problem was because > xfstests 299 was failing earlier on the baseline, and crashing my > regression tests. So I simply commented it out just so I could > complete the testing. It seems that xfstests 299 is problematic for > me, and I need to focus on how to make it pass successfully. (Dmitry, > when I revert the commit which you identified, xfstests 299 is *still* > failing for me....) In fact generic/299 always succeed for me, but it produce warning WARNING: at fs/ext4/inode.c:3218 ext4_ext_direct_IO and complains from slab debug. But it was missed because i've missed this error in the logs and forget to check /proc/sys/kernel/tained. > > - Ted > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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
