Messages in this thread |  | | Date | Tue, 24 Jun 2014 11:06:15 -0400 | | From | Dave Jones <> | | Subject | Re: [PATCH] panic: add TAINT_SOFTLOCKUP |
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On Tue, Jun 24, 2014 at 09:22:20AM -0500, Josh Hunt wrote:
> >> In addition to adding the softlockup taint flag, do you think it'd be > >> reasonable to add another flag for page allocation failures? I think > >> it'd be nice to be able to account for these conditions somehow without > >> having to parse dmesg, etc. As with the softlockup flag, it's helpful to > >> know if your system had encountered a page allocation failure at some > >> point before the crash or whatever you're debugging. > > > > I don't know, really. Allocation failures are often an expected thing > > as drivers try to work out how much memory they can allocate. Those > > things can be screened out by testing __GFP_NOWARN. GFP_ATOMIC > > failures should probably be ignored, except for when they shouldn't. > > But even then, allocation failures are somewhat common. And recency is > > a concern: an allocation failure 10 minutes ago is unlikely to be > > relevant. > > > > But that's just me waving hands around. I'd be interested to hear from > > people whose kernels crash more often than mine, and from those whose > > job is to support them (ie distro people?). > > > > Anyone you'd suggest adding to this thread to get other feedback about > tracking page allocation failures? I could also spin up a patch and cc them.
For things like the fuzz test runs I do, I'd have to patch this out.
Things like migrate_pages() with bad arguments will trigger a page allocation failure rather easily. Likewise set_mempolicy(), and a handful of other vm syscalls.
There's also the case of "too fragmented to satisfy contiguous multi-page allocation" which I walk into from time to time (when the kernel manages to survive a fuzz run long enough, which isn't that often).
Dave
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