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;2.13.6