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Date:   Sat, 7 Oct 2017 09:55:02 +0800
From:   Jia-Ju Bai <>
To:     Linus Torvalds <>
Cc:     Al Viro <>, Jan Kara <>,
        Sagi Grimberg <>,,
        "" <>,
        linux-fsdevel <>,
        Linux Kernel Mailing List <>
Subject: Re: [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in

Thanks for your reply.
I agree that extra allocation in match_number() and match_u64int() may 
be unnecessary.

Jia-Ju Bai

On 2017/10/7 9:37, Linus Torvalds wrote:
> On Fri, Oct 6, 2017 at 6:20 PM, Jia-Ju Bai <> wrote:
>> To fix it, GFP_KERNEL is replaced with GFP_ATOMIC.
>> This bug is found by my static analysis tool and my code review.
> I'm not saying your patch is wrong, but it's a shame that we do that
> extra allocation in match_number() and match_u64int(), and that we
> don't have anything that is just size-limited.
> And there really isn't anything saying that we shouldn't do the same
> silly thing to match_u64int(). Maybe we don't have any actual users
> that need it for now, but still..
> Oh well.
> I do wonder if we shouldn't just use something like
>   "skip leading zeroes, copy to size-limited stack location instead"
> because the input length really *is* limited once you skip leading
> zeroes (and whatever base marker we have). We might have at most a
> 64-bit value in octal, so 22 bytes max.
> But I guess just changing the two GFP_KERNEL's to GFP_ATOMIC is much simpler.
>                 Linus

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