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SubjectRe: [PATCH] mm, memory_hotplug: __offline_pages fix wrong locking
On Tue 15-01-19 13:03:07, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Jan has noticed that we do double unlock on some failure paths when
> offlining a page range. This is indeed the case when test_pages_in_a_zone
> respp. start_isolate_page_range fail. This was an omission when forward
> porting the debugging patch from an older kernel.
>
> Fix the issue by dropping mem_hotplug_done from the failure condition
> and keeping the single unlock in the catch all failure path.
>
> Reported-by: Jan Kara <jack@suse.cz>
> Fixes: 7960509329c2 ("mm, memory_hotplug: print reason for the offlining failure")
> Signed-off-by: Michal Hocko <mhocko@suse.com>

The patch looks good to me so feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Also it fixes the test that previously crashed for me so you can add:

Tested-by: Jan Kara <jack@suse.cz>

Honza


> ---
> mm/memory_hotplug.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index b9a667d36c55..faeeaccc5fae 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1576,7 +1576,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
> we assume this for now. .*/
> if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
> &valid_end)) {
> - mem_hotplug_done();
> ret = -EINVAL;
> reason = "multizone range";
> goto failed_removal;
> @@ -1591,7 +1590,6 @@ static int __ref __offline_pages(unsigned long start_pfn,
> MIGRATE_MOVABLE,
> SKIP_HWPOISON | REPORT_FAILURE);
> if (ret) {
> - mem_hotplug_done();
> reason = "failure to isolate range";
> goto failed_removal;
> }
> --
> 2.20.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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