From: zhong jiang <zhongjiang@huawei.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: hughd@google.com, mhocko@suse.cz, vbabka@suse.cz,
rientjes@google.com, linux-mm@kvack.org
Subject: Re: [PATCH] mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node()
Date: Wed, 28 Sep 2016 10:38:45 +0800 [thread overview]
Message-ID: <57EB2D35.4070006@huawei.com> (raw)
In-Reply-To: <20160920140639.2f1ea83784d994699e713c2e@linux-foundation.org>
On 2016/9/21 5:06, Andrew Morton wrote:
> On Tue, 20 Sep 2016 14:54:44 +0800 zhongjiang <zhongjiang@huawei.com> wrote:
>
>> From: zhong jiang <zhongjiang@huawei.com>
>>
>> Accoding to HUgh's suggestion, alloc_stable_node() with GFP_KERNEL
>> will cause the hungtask, despite less possiblity.
>>
>> At present, if alloc_stable_node allocate fails, two break_cow may
>> want to allocate a couple of pages, and the issue will come up when
>> free memory is under pressure.
>>
>> we fix it by adding the __GFP_HIGH to GFP. because it grant access to
>> some of meory reserves. it will make progess to make it allocation
>> successful at the utmost.
>>
>> --- a/mm/ksm.c
>> +++ b/mm/ksm.c
>> @@ -299,7 +299,7 @@ static inline void free_rmap_item(struct rmap_item *rmap_item)
>>
>> static inline struct stable_node *alloc_stable_node(void)
>> {
>> - return kmem_cache_alloc(stable_node_cache, GFP_KERNEL);
>> + return kmem_cache_alloc(stable_node_cache, GFP_KERNEL | __GFP_HIGH);
>> }
>>
>> static inline void free_stable_node(struct stable_node *stable_node)
> It is very hard for a reader to understand why this __GFP_HIGH is being
> used here, so we should have a code comment explaining the reasoning,
> please.
ok, I will add some code comment later.
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prev parent reply other threads:[~2016-09-28 2:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-20 6:54 [PATCH] mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node() zhongjiang
2016-09-20 20:35 ` Hugh Dickins
2016-09-20 21:06 ` Andrew Morton
2016-09-28 2:38 ` zhong jiang [this message]
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