linux-kernel - Re: [PATCH] xfs: Drop setting redundant PF

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Message-ID: <20170825000137.GI21024@dastard>
Date:   Fri, 25 Aug 2017 10:01:37 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        linux-mm@...ck.org, linux-xfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, dchinner@...hat.com,
        bfoster@...hat.com, sandeen@...deen.net
Subject: Re: [PATCH] xfs: Drop setting redundant PF_KSWAPD in kswapd context

On Thu, Aug 24, 2017 at 12:56:35PM +0200, Michal Hocko wrote:
> On Thu 24-08-17 16:12:47, Anshuman Khandual wrote:
> > xfs_btree_split() calls xfs_btree_split_worker() with args.kswapd set
> > if current->flags alrady has PF_KSWAPD. Hence we should not again add
> > PF_KSWAPD into the current flags inside kswapd context. So drop this
> > redundant flag addition.
> 
> I am not familiar with the code but your change seems incorect. The
> whole point of args->kswapd is to convey the kswapd context to the
> worker which is obviously running in a different context. So this patch
> loses the kswapd context.

Yup. That's what the code does, and removing the PF_KSWAPD from it
will break it.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com