Messages in this thread | | | Date | Tue, 3 Nov 2020 01:33:46 +0100 | From | "Ahmed S. Darwish" <> | Subject | Re: [PATCH v2 2/2] mm: prevent gup_fast from racing with COW during fork |
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On Sat, Oct 31, 2020 at 11:26:05AM -0400, Peter Xu wrote:
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> Shall we document this explicitly (if this patch still needs a repost)?
Yes, this patch series needs a v3 :)
> Seems not straightforward since that seems not the usual way to use seqcount, > not sure whether I'm the only one that feels this way, though.
Yes, this usage is correct but not common. I've proposed a more explicit comment above the write section code, in my reply to patch #2.
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> The other thing is, considering this use of seqcount seems to be quite special > as explained below, I'm just not sure whether this would confuse lockdep or > kcsan, etc., if we decide to use write_seqcount_t_begin(). >
Lockdep won't be confused as it's not used in the raw_*() variant of the seqcount APIs.
AFAIK KCSAN also has some margin to protect itself from this: see seqlock.h KCSAN_SEQLOCK_REGION_MAX.
Thanks,
> Peter Xu
Ahmed Darwish Linutronix GmbH
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