From: Mike Christie <mchristi@redhat.com>
To: Mel Gorman <mgorman@suse.de>, Ilya Dryomov <idryomov@gmail.com>
Cc: ceph-devel@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
Sage Weil <sage@redhat.com>, NeilBrown <neilb@suse.de>,
netdev@vger.kernel.org
Subject: Re: SOCK_MEMALLOC vs loopback
Date: Wed, 04 Mar 2015 22:13:30 -0600 [thread overview]
Message-ID: <54F7D7EA.6010303@redhat.com> (raw)
In-Reply-To: <54F7D5A7.1060404@redhat.com>
On 03/04/2015 10:03 PM, Mike Christie wrote:
> On 03/04/2015 02:04 PM, Mel Gorman wrote:
>> > On Wed, Mar 04, 2015 at 09:38:48PM +0300, Ilya Dryomov wrote:
>>> >> Hello,
>>> >>
>>> >> A short while ago Mike added a patch to libceph to set SOCK_MEMALLOC on
>>> >> libceph sockets and PF_MEMALLOC around send/receive paths (commit
>>> >> 89baaa570ab0, "libceph: use memalloc flags for net IO"). rbd is much
>>> >> like nbd and is succeptible to all the same memory allocation
>>> >> deadlocks, so it seemed like a step in the right direction.
>>> >>
>> >
>> > The contract for SOCK_MEMALLOC is that it would only be used for temporary
>> > allocations that were necessary for the system to make forward progress. In
>> > the case of swap-over-NFS, it would only be used for transmitting
>> > buffers that were necessary to write data to swap when there were no
> Are upper layers like NFS/iSCSI/NBD/RBD supposed to know or track when
> there are no other options (for example if a GFP_ATOMIC allocation
> fails, then set the flags and retry the operation), or are they supposed
> to be able to set the flags, send IO and let the network layer handle it?
>
Oh yeah, maybe I misunderstood you. Were you just saying we should not
be using it for the configuration we are hitting the problem on?
next prev parent reply other threads:[~2015-03-05 4:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-04 18:38 SOCK_MEMALLOC vs loopback Ilya Dryomov
2015-03-04 20:04 ` Mel Gorman
2015-03-05 4:03 ` Mike Christie
2015-03-05 4:13 ` Mike Christie [this message]
2015-03-05 7:09 ` Ilya Dryomov
2015-03-05 9:50 ` Mel Gorman
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