Re: [PATCH 5/6] mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype

[David Hildenbrand]

On 01.09.21 10:02, Miaohe Lin wrote:
> On 2021/8/31 22:23, David Hildenbrand wrote:
> > On 31.08.21 15:43, Mel Gorman wrote:
> > > On Mon, Aug 30, 2021 at 10:10:50PM +0800, Miaohe Lin wrote:
> > > > If it's not prepared to free unref page, the pcp page migratetype is
> > > > unset. Thus We will get rubbish from get_pcppage_migratetype() and
> > > > might list_del &page->lru again after it's already deleted from the
> > > > list leading to grumble about data corruption.
> > > >
> > > > Fixes: 3dcbe270d8ec ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
> > > > Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> > >
> > > Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> > >
> > > This fix is fairly important. Take this patch out and send it on its own
> > > so it gets picked up relatively quickly. It does not belong in a series
> > > that is mostly cosmetic cleanups.
> >
> > I think the commit id is wrong. Shouldn't that be
> >
> > df1acc856923 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
> >
> > ?
>
> Many thanks for pointing this out.
>
> I used to save the git log in a file to make life easier. But it seems this leads
> to the old commit id above.
>
> commit 3dcbe270d8ec57e534f5c605279cdc3ceb1f044a
> Author: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Date:   Fri Jun 4 14:20:03 2021 +1000
>
>      mm/page_alloc: avoid conflating IRQs disabled with zone->lock
>
> git name-rev 3dcbe270d8ec
> 3dcbe270d8ec tags/next-20210604~2^2~196
>
> vs
>
> commit df1acc856923c0a65c28b588585449106c316b71
> Author: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Date:   Mon Jun 28 19:42:00 2021 -0700
>
>      mm/page_alloc: avoid conflating IRQs disabled with zone->lock
>
> git name-rev df1acc856923
> df1acc856923 tags/next-20210630~2^2~278
>
> Their contents are same but with different commit id. The previous one
> could have been git-rebased.

-mm tree commit ids keep changing until patches are upstream. Therefore, 
you can observe changing commit ids in -next. Always use the ones from 
Linus' tree, they are stable.

--
Thanks,

David / dhildenb