From: zijun_hu <zijun_hu@zoho.com>
To: David Rientjes <rientjes@google.com>
Cc: zijun_hu@htc.com, Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org, tj@kernel.org,
mingo@kernel.org, iamjoonsoo.kim@lge.com,
mgorman@techsingularity.net
Subject: Re: [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area()
Date: Thu, 22 Sep 2016 06:35:19 +0800 [thread overview]
Message-ID: <034db3ec-e2dc-a6da-6dab-f0803900e19d@zoho.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1609211408140.20971@chino.kir.corp.google.com>
On 2016/9/22 5:10, David Rientjes wrote:
> On Wed, 21 Sep 2016, zijun_hu wrote:
>
>> From: zijun_hu <zijun_hu@htc.com>
>>
>> correct a few logic error for __insert_vmap_area() since the else
>> if condition is always true and meaningless
>>
>> in order to fix this issue, if vmap_area inserted is lower than one
>> on rbtree then walk around left branch; if higher then right branch
>> otherwise intersects with the other then BUG_ON() is triggered
>>
>
> Under normal operation, you're right that the "else if" conditional should
> always succeed: we don't want to BUG() unless there's a bug. The original
> code can catch instances when va->va_start == tmp_va->va_end where we
> should BUG(). Your code silently ignores it.
>
Hmm, the BUG_ON() appears in the original code, i don't introduce it.
it maybe be better to consider va->va_start == tmp_va->va_end as normal case
and should not BUG_ON() it since the available range of vmap_erea include
the start boundary but the end, BTW, represented as [start, end)
this patch correct the logic to that mentioned in the comments, it maybe be
more logical and more understandable
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next prev parent reply other threads:[~2016-09-21 22:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 4:23 [PATCH 1/5] mm/vmalloc.c: correct a few logic error for __insert_vmap_area() zijun_hu
2016-09-21 21:10 ` David Rientjes
2016-09-21 22:35 ` zijun_hu [this message]
2016-09-21 22:45 ` David Rientjes
2016-09-21 23:10 ` zijun_hu
2016-09-21 23:15 ` David Rientjes
2016-09-21 23:55 ` zijun_hu
2016-09-27 6:07 ` zijun_hu
2016-09-22 1:36 ` [RFC PATCH " zijun_hu
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