Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk

To:	David Miller <davem@xxxxxxxxxxxxx>
Subject:	Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock
From:	NeilBrown <neilb@xxxxxxx>
Date:	Thu, 17 Apr 2014 12:38:37 +1000
Cc:	eric.dumazet@xxxxxxxxx, linux-mm@xxxxxxxxx, linux-nfs@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx
Delivered-to:	xfs@xxxxxxxxxxx
In-reply-to:	<20140416.090002.2186526865564557549.davem@xxxxxxxxxxxxx>
References:	<20140416033623.10604.69237.stgit@xxxxxxxxxxxxxx> <20140416040336.10604.96000.stgit@xxxxxxxxxxxxxx> <1397625226.4222.113.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <20140416.090002.2186526865564557549.davem@xxxxxxxxxxxxx>

On Wed, 16 Apr 2014 09:00:02 -0400 (EDT) David Miller <davem@xxxxxxxxxxxxx>
wrote:

> From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Date: Tue, 15 Apr 2014 22:13:46 -0700
> 
> > For applications handling millions of sockets, this makes a difference.
> 
> Indeed, this really is not acceptable.

As you say...
I've just discovered that I can get rid of the lockdep message (and hence
presumably the deadlock risk) with a well placed:

                newsock->sk->sk_allocation = GFP_NOFS;

which surprised me as it seemed to be an explicit GFP_KERNEL allocation that
was mentioned in the lockdep trace.  Obviously these traces require quite
some sophistication to understand.

So - thanks for the feedback, patch can be ignored.

Thanks,
NeilBrown

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[PATCH 07/19] nfsd and VM: use PF_LESS_THROTTLE to avoid throttle in shrink_inactive_list., (continued) [PATCH 07/19] nfsd and VM: use PF_LESS_THROTTLE to avoid throttle in shrink_inactive_list., NeilBrown [PATCH 08/19] Set PF_FSTRANS while write_cache_pages calls ->writepage, NeilBrown *[PATCH 09/19] XFS: ensure xfs_file__read cannot deadlock in memory allocation.*, NeilBrown* *Re: [PATCH 09/19] XFS: ensure xfs_file__read cannot deadlock in memory allocation.*, Dave Chinner* *Re: [PATCH 09/19] XFS: ensure xfs_file__read cannot deadlock in memory allocation.*, NeilBrown* *Re: [PATCH 09/19] XFS: ensure xfs_file__read cannot deadlock in memory allocation.*, Dave Chinner* [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock, NeilBrown Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock, Eric Dumazet Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock, NeilBrown Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock, David Miller Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock, NeilBrown <= [PATCH 11/19] FS: set PF_FSTRANS while holding mmap_sem in exec.c, NeilBrown [PATCH 12/19] NET: set PF_FSTRANS while holding rtnl_lock, NeilBrown [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock., NeilBrown Re: [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock., Dave Chinner Re: [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock., NeilBrown Re: [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock., Dave Chinner [PATCH 14/19] driver core: set PF_FSTRANS while holding gdp_mutex, NeilBrown [PATCH 15/19] nfsd: set PF_FSTRANS when client_mutex is held., NeilBrown [PATCH 16/19] VFS: use GFP_NOFS rather than GFP_KERNEL in __d_alloc., NeilBrown Re: [PATCH 16/19] VFS: use GFP_NOFS rather than GFP_KERNEL in __d_alloc., Dave Chinner

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Re: [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock