linux-kernel - Re: [PATCH 1/1] mm/migrate: fix list corruption in migration of non-LRU movable pages

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Message-ID: <20190904081408.GF3838@dhcp22.suse.cz>
Date:   Wed, 4 Sep 2019 10:14:08 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     sunqiuyang <sunqiuyang@...wei.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 1/1] mm/migrate: fix list corruption in migration of
 non-LRU movable pages

Do not top post please

On Wed 04-09-19 07:27:25, sunqiuyang wrote:
> isolate_migratepages_block() from another thread may try to isolate the page again:
> 
> for (; low_pfn < end_pfn; low_pfn++) {
>   /* ... */
>   page = pfn_to_page(low_pfn);
>  /* ... */
>   if (!PageLRU(page)) {
>     if (unlikely(__PageMovable(page)) && !PageIsolated(page)) {
>         /* ... */
>         if (!isolate_movable_page(page, isolate_mode))
>           goto isolate_success;
>       /*... */
> isolate_success:
>      list_add(&page->lru, &cc->migratepages);
> 
> And this page will be added to another list.
> Or, do you see any reason that the page cannot go through this path?

The page shouldn't be __PageMovable after the migration is done. All the
state should have been transfered to the new page IIUC.
-- 
Michal Hocko
SUSE Labs