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SubjectRe: [PATCH] slab: remove store_stackinfo()
On Tue, 16 Apr 2019, Vlastimil Babka wrote:
> On 4/16/2019 8:50 PM, Thomas Gleixner wrote:
> > On Tue, 16 Apr 2019, Vlastimil Babka wrote:
> >
> >> On 4/16/19 4:22 PM, Qian Cai wrote:
> >>> store_stackinfo() does not seem used in actual SLAB debugging.
> >>> Potentially, it could be added to check_poison_obj() to provide more
> >>> information, but this seems like an overkill due to the declining
> >>> popularity of the SLAB, so just remove it instead.
> >>>
> >>> Signed-off-by: Qian Cai <cai@lca.pw>
> >>
> >> I've acked Thomas' version already which was narrower, but no objection
> >> to remove more stuff on top of that. Linus (and I later in another
> >> thread) already pointed out /proc/slab_allocators. It only takes a look
> >> at add_caller() there to not regret removing that one.
> >
> > The issue why I was looking at this was a krobot complaint about the kernel
> > crashing in that stack store function with my stackguard series applied. It
> > was broken before the stackguard pages already, it just went unnoticed.
> >
> > As you explained, nobody is caring about DEBUG_SLAB + DEBUG_PAGEALLOC
> > anyway, so I'm happy to not care about krobot tripping over it either.
> >
> > So we have 3 options:
> >
> > 1) I ignore it and merge the stack guard series w/o it
> >
> > 2) I can carry the minimal fix or Qian's version in the stackguard
> > branch
> >
> > 3) We ship that minimal fix to Linus right now and then everyone can
> > base their stuff on top independently.
>
> I think #3 is overkill for something that was broken for who knows how long and
> nobody noticed. I'd go with 2) and perhaps Qian's version as nobody AFAIK uses
> the caller+cpu as well as the stack trace.
>
> For Qian's version also:
> Acked-by: Vlastimil Babka <vbabka@suse.cz>

Ok. I'll pick it up and base the stackguard stuff on top.

Thanks,

tglx

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