From: "Michael S. Tsirkin" <mst@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
Pankaj Gupta <pagupta@redhat.com>,
Qemu Developers <qemu-devel@nongnu.org>,
yu.c.zhang@linux.intel.com, Stefan Hajnoczi <stefanha@redhat.com>,
Igor Mammedov <imammedo@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>
Subject: Re: [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()
Date: Tue, 22 Jan 2019 13:47:08 -0500 [thread overview]
Message-ID: <20190122134252-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CAPcyv4iMO1jxKakMOvePUwPx3GuLDSRf=H2HoqenPP-wGV+n_w@mail.gmail.com>
On Tue, Jan 22, 2019 at 09:33:37AM -0800, Dan Williams wrote:
> On Mon, Jan 21, 2019 at 7:27 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> [..]
> > > 2. The reset of cases:
> > > - we will never pass the MAP_SYNC to mmap2
> >
> > I don't see code probing for MAP_SYNC support. Did I miss it?
> > But if all you want is to have old linux ignore MAP_SYNC,
> > I think you got your wish automatically - just do not set
> > MAP_SHARED_VALIDATE.
>
> That will also cause new Linux to ignore MAP_SYNC.
Oh you are right. I missed this point.
And given that these patches do not seem to set MAP_SHARED_VALIDATE
at all I conclude that even though thet set MAP_SYNC
it actually has no effect at all.
So I wonder how they were tested.
Would the contributors care to elaborate?
That would be good info to put in the commit log message.
--
MST
next prev parent reply other threads:[~2019-01-22 18:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-16 8:10 [Qemu-devel] [PATCH V9 0/6] support MAP_SYNC for memory-backend-file Zhang Yi
2019-01-16 8:10 ` [Qemu-devel] [PATCH V9 1/6] numa: Fixed the memory leak of numa error message Zhang Yi
2019-01-16 15:56 ` Michael S. Tsirkin
2019-01-18 17:36 ` Eduardo Habkost
2019-01-16 8:10 ` [Qemu-devel] [PATCH V9 2/6] memory: use sparse feature define RAM_FLAG Zhang Yi
2019-01-16 15:55 ` Michael S. Tsirkin
2019-01-21 6:35 ` Yi Zhang
2019-01-21 20:24 ` Michael S. Tsirkin
2019-01-22 3:25 ` Yi Zhang
2019-01-16 8:10 ` [Qemu-devel] [PATCH V9 3/6] util/mmap-alloc: switch 'shared' to 'flags' parameter Zhang Yi
2019-01-16 15:49 ` Michael S. Tsirkin
2019-01-16 8:10 ` [Qemu-devel] [PATCH V9 4/6] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() Zhang Yi
2019-01-16 15:58 ` Michael S. Tsirkin
2019-01-18 18:11 ` Eduardo Habkost
2019-01-21 5:15 ` Yi Zhang
2019-01-21 14:44 ` Eduardo Habkost
2019-01-22 3:21 ` Yi Zhang
2019-01-22 3:27 ` Michael S. Tsirkin
2019-01-22 17:33 ` Dan Williams
2019-01-22 18:47 ` Michael S. Tsirkin [this message]
2019-01-16 8:11 ` [Qemu-devel] [PATCH V9 5/6] hostmem: add more information in error messages Zhang Yi
2019-01-16 11:30 ` Stefano Garzarella
2019-01-16 8:11 ` [Qemu-devel] [PATCH V9 6/6] docs: Added MAP_SYNC documentation Zhang Yi
2019-01-16 15:40 ` Michael S. Tsirkin
2019-01-21 6:11 ` Yi Zhang
2019-01-21 7:21 ` Pankaj Gupta
2019-01-21 7:57 ` Yi Zhang
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