From: Andrew Morton <akpm@linux-foundation.org>
To: zijun_hu <zijun_hu@zoho.com>
Cc: tj@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
zijun_hu@htc.com, cl@linux.com
Subject: Re: [RFC v2 PATCH] mm/percpu.c: fix panic triggered by BUG_ON() falsely
Date: Wed, 12 Oct 2016 14:41:12 -0700 [thread overview]
Message-ID: <20161012144112.0494082cf4cbd07609d2405d@linux-foundation.org> (raw)
In-Reply-To: <57FCF07C.2020103@zoho.com>
On Tue, 11 Oct 2016 22:00:28 +0800 zijun_hu <zijun_hu@zoho.com> wrote:
> as shown by pcpu_build_alloc_info(), the number of units within a percpu
> group is educed by rounding up the number of CPUs within the group to
> @upa boundary, therefore, the number of CPUs isn't equal to the units's
> if it isn't aligned to @upa normally. however, pcpu_page_first_chunk()
> uses BUG_ON() to assert one number is equal the other roughly, so a panic
> is maybe triggered by the BUG_ON() falsely.
>
> in order to fix this issue, the number of CPUs is rounded up then compared
> with units's, the BUG_ON() is replaced by warning and returning error code
> as well to keep system alive as much as possible.
Under what circumstances is the triggered? In other words, what are
the end-user visible effects of the fix?
I mean, this is pretty old code (isn't it?) so what are you doing that
triggers this?
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next prev parent reply other threads:[~2016-10-12 21:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-11 14:00 zijun_hu
2016-10-12 21:41 ` Andrew Morton [this message]
2016-10-13 0:05 ` zijun_hu
2016-10-13 0:09 ` zijun_hu
2016-10-13 23:29 ` Tejun Heo
2016-10-14 0:06 ` zijun_hu
2016-10-14 0:24 ` Tejun Heo
2016-10-14 0:52 ` zijun_hu
2016-10-14 0:15 ` zijun_hu
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