Re: [PATCH] Revert "mm/page_isolation: unset migratetype directly for non Buddy page"

[Chen Wandun]

在 2022/1/26 0:40, Vlastimil Babka 写道:
> On 1/17/22 15:27, Chen Wandun wrote:
> > This reverts commit 075782149abff45ee22f27315eced44d02b96779.
> >
> > commit 075782149abf ("mm/page_isolation: unset migratetype directly for
> That's an old -next commit id, it went to mainline as 721fb891ad0b
> ("mm/page_isolation: unset migratetype directly for non Buddy page")
>
> > non Buddy page") will result memory that should in buddy disappear by
> > mistake. move_freepages_block move all pages in pageblock instead of
> > pages indicated by input parameter, so if input pages is not in buddy
> > but other pages in pageblock is in buddy, it will result in page out of
> > control.
> >
> > Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx>
> > Signed-off-by: Chen Wandun <chenwandun@xxxxxxxxxx>
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> #regzbot ^introduced: 721fb891ad0b
>
> There should better be also:
>
> Fixes: 721fb891ad0b ("mm/page_isolation: unset migratetype directly for non
> Buddy page")
>
> Especially as that commit had a (inadequate, IMHO, for an optimization)
> Fixes: tag and could end up being backported somewhere without the followup
> fix/revert.
thanks, I will send v2
> > ---
> >   mm/page_isolation.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> > index 6a0ddda6b3c5..f67c4c70f17f 100644
> > --- a/mm/page_isolation.c
> > +++ b/mm/page_isolation.c
> > @@ -115,7 +115,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
> >   	 * onlining - just onlined memory won't immediately be considered for
> >   	 * allocation.
> >   	 */
> > -	if (!isolated_page && PageBuddy(page)) {
> > +	if (!isolated_page) {
> >   		nr_pages = move_freepages_block(zone, page, migratetype, NULL);
> >   		__mod_zone_freepage_state(zone, nr_pages, migratetype);
> >   	}
> .