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From: David Woodhouse <dwmw2@infradead.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>, Wei Liu <wl@xen.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Jeff Kubascik <jeff.kubascik@dornerworks.com>,
	Stewart Hildebrand <stewart.hildebrand@dornerworks.com>,
	xen-devel@lists.xenproject.org
Subject: Re: [Xen-devel] [XEN PATCH v2 1/2] Check zone before merging adjacent blocks in heap
Date: Wed, 05 Feb 2020 10:24:14 +0000	[thread overview]
Message-ID: <59013bb7dbf9b79daa6dd280c4448418aa1fc56b.camel@infradead.org> (raw)
In-Reply-To: <eff7962d-c6e8-c185-43b6-5c851423cddd@suse.com>


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On Wed, 2020-02-05 at 11:02 +0100, Jan Beulich wrote:
> > +    /* Pages from the boot allocator need to pass through init_heap_pages() */
> > +    if ( unlikely(!pg->count_info) )
> 
> ... while I think this check may be fine here, no similar one
> can be used in free_domheap_pages(), yet pages getting handed
> there isn't less likely than ones getting handed to
> free_xenheap_pages() (if we already fear mismatch).

Do we care about that?

ICBW but I don't think I've seen a case where boot-allocated pages get
handed to free_domheap_pages() later. I've only seen them handed to
free_xenheap_pages(). These are pages which are mapped to Xen, not
domheap pages.

You are already expected *not* to conflate free_xenheap_pages() and
free_domheap_pages().

I think it should be OK to declare that freeing boot-allocated pages
with free_xenheap_pages() is permitted, but freeing them with
free_domheap_pages() isn't.

(Note my straw man patch didn't fix the CONFIG_SEPARATE_XENHEAP case
and doesn't trivially port to that version of free_xenheap_pages()
because the PGC_xen_heap flag isn't used there. But it's fixable
relatively easily.




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  reply	other threads:[~2020-02-05 10:24 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 15:14 [Xen-devel] [XEN PATCH v2 1/2] Check zone before merging adjacent blocks in heap Stewart Hildebrand
2020-02-04 15:14 ` [Xen-devel] [DO NOT APPLY XEN PATCH v2 2/2] Test case for buddy allocator merging issue Stewart Hildebrand
2020-02-04 15:22 ` [Xen-devel] [XEN PATCH v2 1/2] Check zone before merging adjacent blocks in heap Jan Beulich
2020-02-04 15:37   ` George Dunlap
2020-02-05  9:50     ` David Woodhouse
2020-02-05 10:02       ` Jan Beulich
2020-02-05 10:24         ` David Woodhouse [this message]
2020-02-05 10:49           ` Jan Beulich
2020-02-05 11:23             ` David Woodhouse
2020-02-05 13:37               ` Jan Beulich
2020-02-05 14:12                 ` David Woodhouse
2020-02-07 15:49                   ` David Woodhouse
2020-02-07 15:57                     ` [Xen-devel] [PATCH 1/2] xen/mm: fold PGC_broken into PGC_state bits David Woodhouse
2020-02-07 20:27                       ` Julien Grall
2020-02-09 13:22                         ` David Woodhouse
2020-02-09 17:59                           ` Julien Grall
2020-03-17 21:39                         ` David Woodhouse
2020-02-20 11:10                       ` Jan Beulich
2020-03-17 21:52                         ` David Woodhouse
2020-03-18  9:56                           ` Jan Beulich
2020-03-18 12:31                             ` Julien Grall
2020-03-18 13:23                               ` Jan Beulich
2020-03-18 17:13                               ` David Woodhouse
2020-03-19  8:49                                 ` Jan Beulich
2020-03-19 10:26                                   ` David Woodhouse
2020-03-19 11:59                                     ` Jan Beulich
2020-03-19 13:54                                       ` David Woodhouse
2020-03-19 14:46                                         ` Jan Beulich
2020-02-07 15:57                     ` [Xen-devel] [PATCH 2/2] xen/mm: Introduce PG_state_uninitialised David Woodhouse
2020-02-07 16:30                       ` Xia, Hongyan
2020-02-07 16:32                         ` David Woodhouse
2020-02-07 16:40                           ` Xia, Hongyan
2020-02-07 17:06                             ` David Woodhouse
2020-02-07 18:04                               ` David Woodhouse
2020-02-20 11:59                                 ` Jan Beulich
2020-02-20 13:27                                   ` Julien Grall
2020-03-17 22:15                                   ` David Woodhouse
2020-03-18  8:53                                     ` Paul Durrant
2020-03-18 10:10                                       ` Jan Beulich
2020-03-18 10:41                                         ` Paul Durrant
2020-03-18 11:12                                           ` Jan Beulich
2020-03-18 10:03                                     ` Jan Beulich
2020-03-18 12:11                                       ` David Woodhouse
2020-03-18 13:27                                         ` Jan Beulich
2020-02-05 10:22       ` [Xen-devel] [XEN PATCH v2 1/2] Check zone before merging adjacent blocks in heap Julien Grall
2020-02-05 10:32         ` David Woodhouse
2020-02-05 11:36         ` David Woodhouse
2020-02-04 15:37   ` Stewart Hildebrand

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