From: Michal Hocko <mhocko@kernel.org> To: Mike Kravetz <mike.kravetz@oracle.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Vlastimil Babka <vbabka@suse.cz>, Michal Nazarewicz <mina86@mina86.com>, Mel Gorman <mgorman@techsingularity.net>, Johannes Weiner <hannes@cmpxchg.org>, Andrew Morton <akpm@linux-foundation.org>, stable@vger.kernel.org Subject: Re: [PATCH 1/1] mm/cma: fix alloc_contig_range ret code/potential leak Date: Tue, 21 Nov 2017 14:04:18 +0100 [thread overview] Message-ID: <20171121130418.ythozkqb4phpwth4@dhcp22.suse.cz> (raw) In-Reply-To: <20171120193930.23428-2-mike.kravetz@oracle.com> On Mon 20-11-17 11:39:30, Mike Kravetz wrote: > If the call __alloc_contig_migrate_range() in alloc_contig_range > returns -EBUSY, processing continues so that test_pages_isolated() > is called where there is a tracepoint to identify the busy pages. > However, it is possible for busy pages to become available between > the calls to these two routines. In this case, the range of pages > may be allocated. Unfortunately, the original return code (ret > == -EBUSY) is still set and returned to the caller. Therefore, > the caller believes the pages were not allocated and they are leaked. > > Update the return code with the value from test_pages_isolated(). I find the description in 0/0 much more easier to grasp so I would vote for merging it into the changelog. It took me a while to realize that we are talking about the success path just from staring into the diff which doesn't have a sufficient scope to tell the whole story. Btw. I find embeded description in the diffstat area much more easier to follow for single patches. Having a cover for a single patch sounds more like a distraction. Just my 2c > Fixes: 8ef5849fa8a2 ("mm/cma: always check which page caused allocation failure") > Cc: <stable@vger.kernel.org> > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/page_alloc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 77e4d3c5c57b..3605ca82fd29 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7632,10 +7632,10 @@ int alloc_contig_range(unsigned long start, unsigned long end, > } > > /* Make sure the range is really isolated. */ > - if (test_pages_isolated(outer_start, end, false)) { > + ret = test_pages_isolated(outer_start, end, false); > + if (ret) { > pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", > __func__, outer_start, end); > - ret = -EBUSY; > goto done; > } > > -- > 2.13.6 > -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Mike Kravetz <mike.kravetz@oracle.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Vlastimil Babka <vbabka@suse.cz>, Michal Nazarewicz <mina86@mina86.com>, Mel Gorman <mgorman@techsingularity.net>, Johannes Weiner <hannes@cmpxchg.org>, Andrew Morton <akpm@linux-foundation.org>, stable@vger.kernel.org Subject: Re: [PATCH 1/1] mm/cma: fix alloc_contig_range ret code/potential leak Date: Tue, 21 Nov 2017 14:04:18 +0100 [thread overview] Message-ID: <20171121130418.ythozkqb4phpwth4@dhcp22.suse.cz> (raw) In-Reply-To: <20171120193930.23428-2-mike.kravetz@oracle.com> On Mon 20-11-17 11:39:30, Mike Kravetz wrote: > If the call __alloc_contig_migrate_range() in alloc_contig_range > returns -EBUSY, processing continues so that test_pages_isolated() > is called where there is a tracepoint to identify the busy pages. > However, it is possible for busy pages to become available between > the calls to these two routines. In this case, the range of pages > may be allocated. Unfortunately, the original return code (ret > == -EBUSY) is still set and returned to the caller. Therefore, > the caller believes the pages were not allocated and they are leaked. > > Update the return code with the value from test_pages_isolated(). I find the description in 0/0 much more easier to grasp so I would vote for merging it into the changelog. It took me a while to realize that we are talking about the success path just from staring into the diff which doesn't have a sufficient scope to tell the whole story. Btw. I find embeded description in the diffstat area much more easier to follow for single patches. Having a cover for a single patch sounds more like a distraction. Just my 2c > Fixes: 8ef5849fa8a2 ("mm/cma: always check which page caused allocation failure") > Cc: <stable@vger.kernel.org> > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/page_alloc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 77e4d3c5c57b..3605ca82fd29 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7632,10 +7632,10 @@ int alloc_contig_range(unsigned long start, unsigned long end, > } > > /* Make sure the range is really isolated. */ > - if (test_pages_isolated(outer_start, end, false)) { > + ret = test_pages_isolated(outer_start, end, false); > + if (ret) { > pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n", > __func__, outer_start, end); > - ret = -EBUSY; > goto done; > } > > -- > 2.13.6 > -- Michal Hocko SUSE Labs -- 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:[~2017-11-21 13:04 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-20 19:39 [PATCH 0/1] mm/cma: fix alloc_contig_range ret code/potential leak Mike Kravetz 2017-11-20 19:39 ` Mike Kravetz 2017-11-20 19:39 ` [PATCH 1/1] " Mike Kravetz 2017-11-20 19:39 ` Mike Kravetz 2017-11-21 7:53 ` Vlastimil Babka 2017-11-21 7:53 ` Vlastimil Babka 2017-11-21 13:06 ` Michal Hocko 2017-11-21 13:06 ` Michal Hocko 2017-11-21 13:04 ` Michal Hocko [this message] 2017-11-21 13:04 ` Michal Hocko 2017-11-21 14:20 ` Michal Nazarewicz 2017-11-21 14:20 ` Michal Nazarewicz 2017-11-21 14:20 ` Michal Nazarewicz 2017-11-22 12:00 ` Johannes Weiner 2017-11-22 12:00 ` Johannes Weiner 2017-11-22 17:46 ` Mike Kravetz 2017-11-22 17:46 ` Mike Kravetz 2017-11-22 18:52 ` [PATCH v2] " Mike Kravetz 2017-11-22 18:52 ` Mike Kravetz 2017-11-23 8:05 ` Vlastimil Babka 2017-11-23 8:05 ` Vlastimil Babka 2017-11-23 9:19 ` Michal Hocko 2017-11-23 9:19 ` Michal Hocko 2017-11-27 16:59 ` Johannes Weiner 2017-11-27 16:59 ` Johannes Weiner 2017-11-29 5:38 ` Joonsoo Kim 2017-11-29 5:38 ` Joonsoo Kim
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