Re: [Xen-devel] linux 4.19 xenstore memory allocation failure Re: [linux-4.19 test] 135420: regressions - FAIL

[Ian Jackson <ian.jackson@xxxxxxxxxx>]

Jan Beulich writes ("Re: [Xen-devel] linux 4.19 xenstore memory allocation 
failure Re: [linux-4.19 test] 135420: regressions - FAIL"):
> On 30.04.19 at 15:02, <ian.jackson@xxxxxxxxxx> wrote:
> > ISTM that there are *two* bugs here:
> > 
> >  1. Whatever caused the memory allocation failure
> 
> An order-5 allocation is set to fail at any time (afaict). I find it
> surprising that struct blkfront_ring_info instances (even arrays
> of them when using multiple rings) get allocated using kcalloc()
> rather than kvcalloc(), considering the size of the structure
> (0x140E0 according to the disassembly of the 5.0.1 driver I
> had to hand).

I will leave answering this to the blkfront/linux folks...

> >  2. That a memory allocation failure can cause permanent loss of a
> >      xenstore watch event
> 
> Well, isn't it sort of expected that an allocation failure will lead
> to further problems?

I would have hoped that it would result in something other than a
hang.  At worst, blkfront ought to go into a state where it *knows*
that it is utterly broken and reports this properly.

Ian.

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