From: Jia-Ju Bai <baijiaju1990@163.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: akpm@linux-foundation.org, mhocko@suse.com, mingo@kernel.org,
catalin.marinas@arm.com, labbott@redhat.com, thgarnie@google.com,
kirill.shutemov@linux.intel.com, aryabinin@virtuozzo.com,
ard.biesheuvel@linaro.org, zijun_hu@htc.com, linux-mm@kvack.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] mm/vmalloc: ___might_sleep is called under a spinlock in __purge_vmap_area_lazy
Date: Mon, 9 Oct 2017 12:48:22 +0800 [thread overview]
Message-ID: <56ef9c88-ba54-ce01-15dc-7b661b64ab8b@163.com> (raw)
In-Reply-To: <20171009041001.p47yc6r7f3borhba@node.shutemov.name>
Thanks for your reply and explanation :)
I will improve my analysis.
Thanks,
Jia-Ju Bai
On 2017/10/9 12:10, Kirill A. Shutemov wrote:
> On Mon, Oct 09, 2017 at 12:00:33PM +0800, Jia-Ju Bai wrote:
>> The ___might_sleep is called under a spinlock, and the function call graph
>> is:
>> __purge_vmap_area_lazy (acquire the spinlock)
>> cond_resched_lock
>> ___might_sleep
>>
>> In this situation, ___might_sleep may prints error log message because a
>> spinlock is held.
>> A possible fix is to remove ___might_sleep in cond_resched_lock.
>>
>> This bug is found by my static analysis tool and my code review.
> This analysis doesn't makes sense.
>
> The point of cond_resched_lock() is that it drops the lock, if resched is
> required.
>
> ___might_sleep() is called with preempt_offset equal to
> PREEMPT_LOCK_OFFSET, so it won't report error if it's the only lock we
> hold.
>
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prev parent reply other threads:[~2017-10-09 4:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-09 4:00 Jia-Ju Bai
2017-10-09 4:10 ` Kirill A. Shutemov
2017-10-09 4:48 ` Jia-Ju Bai [this message]
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