________________________________________
From: Michal Hocko [mhocko@xxxxxxxxxx]
Sent: Wednesday, September 04, 2019 16:14
To: sunqiuyang
Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx
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.
----
I don't see where page->mapping is modified after the migration is done.
Actually, the last comment in move_to_new_page() says,
"Anonymous and movable page->mapping will be cleard by
free_pages_prepare so don't reset it here for keeping
the type to work PageAnon, for example. "
Or did I miss something? Thanks,
--
Michal Hocko
SUSE Labs
