From: Vlastimil Babka <vbabka@suse.cz> To: yalin wang <yalin.wang2010@gmail.com>, akpm@linux-foundation.org, mgorman@techsingularity.net, mhocko@suse.com, rientjes@google.com, js1304@gmail.com, kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, alexander.h.duyck@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] mm: fix a BUG, the page is allocated 2 times Date: Mon, 12 Oct 2015 09:38:33 +0200 [thread overview] Message-ID: <561B6379.2070407@suse.cz> (raw) In-Reply-To: <1444617606-8685-1-git-send-email-yalin.wang2010@gmail.com> On 10/12/2015 04:40 AM, yalin wang wrote: > Remove unlikely(order), because we are sure order is not zero if > code reach here, also add if (page == NULL), only allocate page again if > __rmqueue_smallest() failed or alloc_flags & ALLOC_HARDER == 0 The second mentioned change is actually more important as it removes a memory leak! Thanks for catching this. The problem is in patch mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch and seems to have been due to a change in the last submitted version to make sure the tracepoint is called. > Signed-off-by: yalin wang <yalin.wang2010@gmail.com> > --- > mm/page_alloc.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0d6f540..de82e2c 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2241,13 +2241,13 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, > spin_lock_irqsave(&zone->lock, flags); > > page = NULL; > - if (unlikely(order) && (alloc_flags & ALLOC_HARDER)) { > + if (alloc_flags & ALLOC_HARDER) { > page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); > if (page) > trace_mm_page_alloc_zone_locked(page, order, migratetype); > } > - > - page = __rmqueue(zone, order, migratetype, gfp_flags); > + if (page == NULL) "if (!page)" is more common and already used below. We could skip the check for !page in case we don't go through the ALLOC_HARDER branch, but I guess it's not worth the goto, and hopefully the compiler is smart enough anyway... > + page = __rmqueue(zone, order, migratetype, gfp_flags); > spin_unlock(&zone->lock); > if (!page) > goto failed; >
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz> To: yalin wang <yalin.wang2010@gmail.com>, akpm@linux-foundation.org, mgorman@techsingularity.net, mhocko@suse.com, rientjes@google.com, js1304@gmail.com, kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, alexander.h.duyck@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] mm: fix a BUG, the page is allocated 2 times Date: Mon, 12 Oct 2015 09:38:33 +0200 [thread overview] Message-ID: <561B6379.2070407@suse.cz> (raw) In-Reply-To: <1444617606-8685-1-git-send-email-yalin.wang2010@gmail.com> On 10/12/2015 04:40 AM, yalin wang wrote: > Remove unlikely(order), because we are sure order is not zero if > code reach here, also add if (page == NULL), only allocate page again if > __rmqueue_smallest() failed or alloc_flags & ALLOC_HARDER == 0 The second mentioned change is actually more important as it removes a memory leak! Thanks for catching this. The problem is in patch mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch and seems to have been due to a change in the last submitted version to make sure the tracepoint is called. > Signed-off-by: yalin wang <yalin.wang2010@gmail.com> > --- > mm/page_alloc.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 0d6f540..de82e2c 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2241,13 +2241,13 @@ struct page *buffered_rmqueue(struct zone *preferred_zone, > spin_lock_irqsave(&zone->lock, flags); > > page = NULL; > - if (unlikely(order) && (alloc_flags & ALLOC_HARDER)) { > + if (alloc_flags & ALLOC_HARDER) { > page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); > if (page) > trace_mm_page_alloc_zone_locked(page, order, migratetype); > } > - > - page = __rmqueue(zone, order, migratetype, gfp_flags); > + if (page == NULL) "if (!page)" is more common and already used below. We could skip the check for !page in case we don't go through the ALLOC_HARDER branch, but I guess it's not worth the goto, and hopefully the compiler is smart enough anyway... > + page = __rmqueue(zone, order, migratetype, gfp_flags); > spin_unlock(&zone->lock); > if (!page) > goto failed; > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-10-12 7:38 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-10-12 2:40 [RFC] mm: fix a BUG, the page is allocated 2 times yalin wang 2015-10-12 2:40 ` yalin wang 2015-10-12 7:38 ` Vlastimil Babka [this message] 2015-10-12 7:38 ` Vlastimil Babka 2015-10-12 7:58 ` yalin wang 2015-10-12 7:58 ` yalin wang 2015-10-12 10:05 ` Kirill A. Shutemov 2015-10-12 10:05 ` Kirill A. Shutemov 2015-10-12 11:22 ` Vlastimil Babka 2015-10-12 11:22 ` Vlastimil Babka 2015-10-12 13:52 ` Mel Gorman 2015-10-12 13:52 ` Mel Gorman 2015-10-13 1:43 ` yalin wang 2015-10-13 1:43 ` yalin wang
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