Re: [LKP] [mm] cc87317726f: WARNING: CPU: 0 PID: 1 at drivers/iommu/io-pgtable-arm.c:413 __arm_lpae_unmap+0x341/0x380()

[Huang Ying]

On Tue, 2015-03-17 at 15:24 -0400, Johannes Weiner wrote:
> On Tue, Mar 17, 2015 at 10:15:29AM -0700, Linus Torvalds wrote:
> > Explicitly adding the emails of other people involved with that commit
> > and the original oom thread to make sure people are aware, since this
> > didn't get any response.
> > 
> > Commit cc87317726f8 fixed some behavior, but also seems to have turned
> > an oom situation into a complete hang. So presumably we shouldn't loop
> > *forever*. Hmm?
> 
> It seems we are between a rock and a hard place here, as we reverted
> specifically to that endless looping on request of filesystem people.
> They said[1] they rely on these allocations never returning NULL, or
> they might fail inside a transactions and corrupt on-disk data.
> 
> Huang, against which kernels did you first run this test on this exact
> setup?  Is there a chance you could try to run a kernel without/before
> 9879de7373fc?  I want to make sure I'm not missing something, but all
> versions preceding this commit should also have the same hang.  There
> should only be a tiny window between 9879de7373fc and cc87317726f8 --
> v3.19 -- where these allocations are allowed to fail.

I checked the test result of v3.19-rc6.  It shows that boot will hang at
the same position.

BTW: the test is run on 32 bit system.

Best Regards,
Huang, Ying


--
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/