From: Michal Hocko <mhocko@suse.cz>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, memcg: sync allocation and memcg charge gfp flags for THP
Date: Wed, 18 Mar 2015 16:59:05 +0100 [thread overview]
Message-ID: <20150318155905.GO17241@dhcp22.suse.cz> (raw)
In-Reply-To: <55099C72.1080102@suse.cz>
On Wed 18-03-15 16:40:34, Vlastimil Babka wrote:
> On 03/18/2015 04:02 PM, Michal Hocko wrote:
> >On Wed 18-03-15 15:34:50, Vlastimil Babka wrote:
> >>On 03/16/2015 03:08 PM, Michal Hocko wrote:
> >>>@@ -1080,6 +1080,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> >>> unsigned long haddr;
> >>> unsigned long mmun_start; /* For mmu_notifiers */
> >>> unsigned long mmun_end; /* For mmu_notifiers */
> >>>+ gfp_t huge_gfp = GFP_TRANSHUGE; /* for allocation and charge */
> >>
> >>This value is actually never used. Is it here because the compiler emits a
> >>spurious non-initialized value warning otherwise? It should be easy for it
> >>to prove that setting new_page to something non-null implies initializing
> >>huge_gfp (in the hunk below), and NULL new_page means it doesn't reach the
> >>mem_cgroup_try_charge() call?
> >
> >No, I haven't tried to workaround the compiler. It just made the code
> >more obvious to me. I can remove the initialization if you prefer, of
> >course.
>
> Yeah IMHO it would be better to remove it, if possible. Leaving it has the
> (albeit small) chance that future patch will again use the value in the code
> before it's determined based on defrag setting.
Wouldn't an uninitialized value be used in such a case?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2015-03-18 15:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-16 14:08 [PATCH] mm, memcg: sync allocation and memcg charge gfp flags for THP Michal Hocko
2015-03-18 14:34 ` Vlastimil Babka
2015-03-18 15:02 ` Michal Hocko
2015-03-18 15:40 ` Vlastimil Babka
2015-03-18 15:59 ` Michal Hocko [this message]
2015-03-18 16:09 ` Vlastimil Babka
2015-03-18 16:14 ` [PATCH -v2] " Michal Hocko
2015-04-03 1:41 ` [patch] mm, memcg: sync allocation and memcg charge gfp flags for thp fix fix David Rientjes
2015-04-03 8:38 ` Vlastimil Babka
2015-04-03 10:50 ` Michal Hocko
2015-04-04 1:34 ` [PATCH -v2] mm, memcg: sync allocation and memcg charge gfp flags for THP David Rientjes
2015-04-07 12:19 ` Michal Hocko
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