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Subject: Re: RE: [PATCH net 0/2] Revert the 'socket_alloc' life cycle change
From:   SeongJae Park <sjpark@amazon.com>
To:     Al Viro <viro@zeniv.linux.org.uk>
CC:     SeongJae Park <sjpark@amazon.com>, <davem@davemloft.net>,
        <kuba@kernel.org>, <gregkh@linuxfoundation.org>,
        <edumazet@google.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, SeongJae Park <sjpark@amazon.de>
Date:   Tue, 5 May 2020 16:24:37 +0200
Message-ID: <20200505142437.22822-1-sjpark@amazon.com>
In-Reply-To: <20200505124442.GX23230@ZenIV.linux.org.uk>
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On Tue, 5 May 2020 13:44:42 +0100 Al Viro <viro@zeniv.linux.org.uk> wrote:

> CAUTION: This email originated from outside of the organization. Do not cli=
> ck links or open attachments unless you can confirm the sender and know the=
>  content is safe.
> 
> 
> 
> On Tue, May 05, 2020 at 09:28:39AM +0200, SeongJae Park wrote:
> > From: SeongJae Park <sjpark@amazon.de>
> >
> > The commit 6d7855c54e1e ("sockfs: switch to ->free_inode()") made the
> > deallocation of 'socket_alloc' to be done asynchronously using RCU, as
> > same to 'sock.wq'.  And the following commit 333f7909a857 ("coallocate
> > socket_sq with socket itself") made those to have same life cycle.
> >
> > The changes made the code much more simple, but also made 'socket_alloc'
> > live longer than before.  For the reason, user programs intensively
> > repeating allocations and deallocations of sockets could cause memory
> > pressure on recent kernels.
> >
> > To avoid the problem, this commit reverts the changes.
> 
> Is it "could cause" or is it "have been actually observed to"?

Actually observed.  Sorry for lack of that explanation.  Could you please refer
to this link?
https://lore.kernel.org/netdev/20200505115402.25768-1-sjpark@amazon.com/


Thanks,
SeongJae Park