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Groups > linux.kernel > #1402777
| From | Vlastimil Babka <vbabka@suse.cz> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP |
| Date | 2016-05-18 10:00 +0200 |
| Message-ID | <rA4yB-7yy-7@gated-at.bofh.it> (permalink) |
| References | <ro7LB-hc-17@gated-at.bofh.it> <ro7Vg-Er-9@gated-at.bofh.it> <ro850-In-85@gated-at.bofh.it> <rzH90-16V-13@gated-at.bofh.it> <rA4yB-7yy-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 05/18/2016 09:51 AM, Vlastimil Babka wrote:
> ----8<----
> From f52f5e2a7dd65f2814183d8fd254ace43120b828 Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@suse.cz>
> Date: Wed, 18 May 2016 09:41:01 +0200
> Subject: [PATCH] mm, page_alloc: prevent infinite loop in buffered_rmqueue()
>
> In DEBUG_VM kernel, we can hit infinite loop for order == 0 in
> buffered_rmqueue() when check_new_pcp() returns 1, because the bad page is
> never removed from the pcp list. Fix this by removing the page before retrying.
> Also we don't need to check if page is non-NULL, because we simply grab it from
> the list which was just tested for being non-empty.
>
> Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-freed-pages-until-a-pcp-drain.patch
Wrong.
Fixes: http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-defer-debugging-checks-of-pages-allocated-from-the-pcp.patch
> Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/page_alloc.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8c81e2e7b172..d5b93e5dd697 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2641,11 +2641,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
> page = list_last_entry(list, struct page, lru);
> else
> page = list_first_entry(list, struct page, lru);
> - } while (page && check_new_pcp(page));
>
> - __dec_zone_state(zone, NR_ALLOC_BATCH);
> - list_del(&page->lru);
> - pcp->count--;
> + __dec_zone_state(zone, NR_ALLOC_BATCH);
> + list_del(&page->lru);
> + pcp->count--;
> +
> + } while (check_new_pcp(page));
> } else {
> /*
> * We most definitely don't want callers attempting to
>
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Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> - 2016-05-17 09:00 +0200
Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Vlastimil Babka <vbabka@suse.cz> - 2016-05-18 10:00 +0200
Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Vlastimil Babka <vbabka@suse.cz> - 2016-05-18 10:00 +0200
Re: [PATCH 28/28] mm, page_alloc: Defer debugging checks of pages allocated from the PCP Mel Gorman <mgorman@techsingularity.net> - 2016-05-18 10:50 +0200
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