2014-09-27 7:02 GMT+04:00 Sasha Levin [off-list ref]:

On 09/22/2014 07:04 PM, Hugh Dickins wrote:

quoted

quoted

but I'm not sure what went wrong.

Most likely would be a zeroing of the radix_tree node, just as you
were experiencing zeroing of other mm structures in earlier weeks.

Not that I've got any suggestions on where to take it from there.

I've added poisoning to a few mm related structures, and managed to
confirm that the issue here is indeed corruption rather than something
specific with the given structures.

Right now I'm looking into making KASan (Cc Andrey) to mark the poison
bytes somehow so it would trigger an error on access, that way we'll
know what's corruption them.

Andrey, since it takes a while to trigger this corruption, could you
confirm that if I kasan_poison_shadow() a few bytes I will get a KASan
report on any read/write to them?

That's right. Note that poison value has to be negative.
Address and size of poisoned area has to be aligned to 8 bytes.

-- 
Best regards,
Andrey Ryabinin

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