linux-kernel - Re: [GIT PULL] Please pull NFS client fixes for 4.12

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Message-ID: <be16be57-235c-fdf9-f708-3898aeeeb5aa@gmail.com>
Date:   Thu, 11 May 2017 10:53:27 +0300
From:   Nikolay Borisov <n.borisov.lkml@...il.com>
To:     Trond Myklebust <trondmy@...marydata.com>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [GIT PULL] Please pull NFS client fixes for 4.12



On 10.05.2017 19:47, Trond Myklebust wrote:
> Hi Linus,
> 
> The following changes since commit 4f7d029b9bf009fbee76bb10c0c4351a1870d2f3:
> 
>   Linux 4.11-rc7 (2017-04-16 13:00:18 -0700)
> 
> are available in the git repository at:
> 
>   git://git.linux-nfs.org/projects/trondmy/linux-nfs.git tags/nfs-for-4.12-1
> 
> for you to fetch changes up to 76b2a303384e1d6299c3a0249f0f0ce2f8f96017:
> 
>   pNFS/flexfiles: Always attempt to call layoutstats when flexfiles is enabled (2017-05-09 16:02:57 -0400)
> 
> ----------------------------------------------------------------
> NFS client updates for Linux 4.12
> 
> Highlights include:
> 
> Stable bugfixes:
> - Fix use after free in write error path
> - Use GFP_NOIO for two allocations in writeback
> - Fix a hang in OPEN related to server reboot
> - Check the result of nfs4_pnfs_ds_connect
> - Fix an rcu lock leak
> 
> Features:
> - Removal of the unmaintained and unused OSD pNFS layout
> - Cleanup and removal of lots of unnecessary dprintk()s
> - Cleanup and removal of some memory failure paths now that
>   GFP_NOFS is guaranteed to never fail.

What guarantees that? Since if this is the case then this can result in
a lot of opportunities for cleanup across the whole kernel tree. After
discussing with mhocko (cc'ed) it seems that in practice everything
below COSTLY_ORDER which are not GFP_NORETRY will never fail. But this
semantic is not the same as GFP_NOFAIL. E.g. nothing guarantees that
this will stay like that in the future?



[omitted for brevity]