From: David Laight <David.Laight@ACULAB.COM>
To: 'Vlastimil Babka' <vbabka@suse.cz>, 'Hugh Dickins' <hughd@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: RE: amusing SLUB compaction bug when CC_OPTIMIZE_FOR_SIZE
Date: Thu, 29 Sep 2022 14:04:31 +0000 [thread overview]
Message-ID: <67f53a71f7ae4f518c7e953b8cfce58a@AcuMS.aculab.com> (raw)
In-Reply-To: <ea6e7b10-c514-8320-05c2-4a18391a7079@suse.cz>
From: Vlastimil Babka
> Sent: 29 September 2022 14:01
>
> On 9/29/22 13:53, David Laight wrote:
> >> -static void rcu_free_slab(struct rcu_head *h)
> >> +/*
> >> + * rcu_free_slab() must be __aligned(4) because its address is saved
> >> + * in the rcu_head field, which coincides with page->mapping, which
> >> + * causes trouble if compaction mistakes it for PAGE_MAPPING_MOVABLE.
> >> + */
> >> +__aligned(4) static void rcu_free_slab(struct rcu_head *h)
> >> {
> >> struct slab *slab = container_of(h, struct slab, rcu_head);
> >>
> >
> > Isn't that going to cause grief with options that align
> > functions on 16/32byte boundaries when adding space for
> > 'other stuff'?
>
> How is that done exactly? Also having higher alignment (16/32) is not in
> conflict with asking for 4?
It depends on which one is actually used.
The __aligned(4) might take precedence over the default alignment.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-09-29 14:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-28 5:16 Hugh Dickins
2022-09-28 5:49 ` Hyeonggon Yoo
2022-09-28 13:48 ` Joel Fernandes
2022-09-28 15:09 ` Hyeonggon Yoo
2022-09-28 16:20 ` Vlastimil Babka
2022-09-28 17:50 ` Hugh Dickins
2022-09-29 9:58 ` Vlastimil Babka
2022-09-29 21:54 ` Hugh Dickins
2022-09-30 7:39 ` Vlastimil Babka
2022-09-30 10:45 ` Hugh Dickins
2022-09-30 11:02 ` David Laight
2022-09-30 16:21 ` Hugh Dickins
2022-09-30 21:34 ` David Laight
2022-10-02 5:48 ` Hyeonggon Yoo
2022-10-03 17:00 ` Matthew Wilcox
2022-10-04 14:26 ` Hyeonggon Yoo
2022-10-04 14:40 ` Matthew Wilcox
2022-10-05 11:07 ` Hyeonggon Yoo
2022-10-24 14:35 ` Vlastimil Babka
2022-10-24 15:06 ` Matthew Wilcox
2022-10-24 15:24 ` Vlastimil Babka
2022-10-24 16:49 ` Vlastimil Babka
2022-10-25 4:19 ` Hugh Dickins
2022-10-25 9:17 ` Vlastimil Babka
2022-10-25 15:45 ` Hugh Dickins
2022-10-25 13:47 ` Hyeonggon Yoo
2022-10-25 14:08 ` Vlastimil Babka
2022-10-26 10:52 ` Vlastimil Babka
2022-10-26 12:29 ` Hyeonggon Yoo
2022-11-04 15:57 ` Vlastimil Babka
2022-09-29 11:53 ` David Laight
2022-09-29 13:01 ` Vlastimil Babka
2022-09-29 14:04 ` David Laight [this message]
2022-09-28 17:56 ` Hyeonggon Yoo
2022-09-28 19:53 ` Joel Fernandes
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