From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Jia-Ju Bai <baijiaju1990@163.com>
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 07:10:01 +0300 [thread overview]
Message-ID: <20171009041001.p47yc6r7f3borhba@node.shutemov.name> (raw)
In-Reply-To: <70f9850a-b24c-8595-8a22-9b47e96d6338@163.com>
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.
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2017-10-09 4:10 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 [this message]
2017-10-09 4:48 ` Jia-Ju Bai
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