On Fri, Sep 25, 2020 at 9:32 AM Shakeel Butt <shakeelb@xxxxxxxxxx> wrote: > > On Fri, Sep 25, 2020 at 9:19 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote: > > > > On Fri, Sep 25, 2020 at 03:31:45PM +0800, Ming Lei wrote: > > > On Thu, Sep 24, 2020 at 09:13:11PM -0400, Theodore Y. Ts'o wrote: > > > > On Thu, Sep 24, 2020 at 10:33:45AM -0400, Theodore Y. Ts'o wrote: > > > > > HOWEVER, thanks to a hint from a colleague at $WORK, and realizing > > > > > that one of the stack traces had virtio balloon in the trace, I > > > > > realized that when I switched the GCE VM type from e1-standard-2 to > > > > > n1-standard-2 (where e1 VM's are cheaper because they use > > > > > virtio-balloon to better manage host OS memory utilization), problem > > > > > has become, much, *much* rarer (and possibly has gone away, although > > > > > I'm going to want to run a lot more tests before I say that > > > > > conclusively) on my test setup. At the very least, using an n1 VM > > > > > (which doesn't have virtio-balloon enabled in the hypervisor) is > > > > > enough to unblock ext4 development. > > > > > > > > .... and I spoke too soon. A number of runs using -rc6 are now > > > > failing even with the n1-standard-2 VM, so virtio-ballon may not be an > > > > indicator. > > > > > > > > This is why debugging this is frustrating; it is very much a heisenbug > > > > --- although 5.8 seems to work completely reliably, as does commits > > > > before 37f4a24c2469. Anything after that point will show random > > > > failures. :-( > > > > > > It does not make sense to mention 37f4a24c2469, which is reverted in > > > 4e2f62e566b5. Later the patch in 37f4a24c2469 is fixed and re-commited > > > as 568f27006577. > > > > > > However, I can _not_ reproduce the issue by running the same test on > > > kernel built from 568f27006577 directly. > > > > > > Also you have confirmed that the issue can't be fixed after reverting > > > 568f27006577 against v5.9-rc4. > > > > > > Looks the real issue(slab list corruption) should be introduced between > > > 568f27006577 and v5.9-rc4. > > > > git bisect shows the first bad commit: > > > > [10befea91b61c4e2c2d1df06a2e978d182fcf792] mm: memcg/slab: use a single set of > > kmem_caches for all allocations > > > > And I have double checked that the above commit is really the first bad > > commit for the list corruption issue of 'list_del corruption, ffffe1c241b00408->next > > is LIST_POISON1 (dead000000000100)', see the detailed stack trace and > > kernel oops log in the following link: > > > > https://lore.kernel.org/lkml/20200916202026.GC38283@xxxxxxx/ > > The failure signature is similar to > https://lore.kernel.org/lkml/20200901075321.GL4299@shao2-debian/ > > > > > And the kernel config is the one(without KASAN) used by Theodore in GCE VM, see > > the following link: > > > > https://lore.kernel.org/lkml/20200917143012.GF38283@xxxxxxx/ > > > > The reproducer is xfstests generic/038. In my setting, test device is virtio-scsi, and > > scratch device is virtio-blk. Is it possible to check SLUB as well to confirm that the issue is only happening on SLAB?
