From: Vlastimil Babka <vbabka@suse.cz>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3] mm/thp: Allocate transparent hugepages on local node
Date: Wed, 21 Jan 2015 12:28:05 +0100 [thread overview]
Message-ID: <54BF8D45.7030205@suse.cz> (raw)
In-Reply-To: <54BE1B00.3090102@suse.cz>
On 01/20/2015 10:08 AM, Vlastimil Babka wrote:
> On 01/20/2015 06:52 AM, Aneesh Kumar K.V wrote:
>> Vlastimil Babka <vbabka@suse.cz> writes:
>>
>> is that check correct ? ie,
>>
>> if ((gfp & GFP_TRANSHUGE) == GFP_TRANSHUGE)
>>
>> may not always indicate transparent hugepage if defrag = 0 . With defrag
>> cleared, we remove __GFP_WAIT from GFP_TRANSHUGE.
>
> Yep, that looks wrong. Sigh. I guess we can't spare an extra GFP flag to
> indicate TRANSHUGE?
I wanted to fix this in __alloc_pages_slowpath(), but actually there's no issue
(other than being quite subtle) - if defrag == 0 and thus we don't have
__GFP_WAIT, we reach "if (!wait) goto nopage;" and bail out before reaching the
checks for GFP_TRANSHUGE.
>> static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
>> {
>> return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
>> }
>>
>> -aneesh
>>
>> --
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>
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prev parent reply other threads:[~2015-01-21 11:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-16 7:26 [PATCH V3] mm/thp: Allocate transparent hugepages on local node Aneesh Kumar K.V
2015-01-16 12:27 ` Kirill A. Shutemov
2015-01-16 20:01 ` Vlastimil Babka
2015-01-17 0:02 ` Andrew Morton
2015-01-17 7:15 ` Davidlohr Bueso
2015-01-18 15:50 ` Aneesh Kumar K.V
2015-01-18 15:48 ` Aneesh Kumar K.V
2015-01-19 16:27 ` Vlastimil Babka
2015-01-20 5:52 ` Aneesh Kumar K.V
2015-01-20 9:08 ` Vlastimil Babka
2015-01-21 11:28 ` Vlastimil Babka [this message]
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