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In-Reply-To: <20210114165645.czqpsk3lacmiyiik@linutronix.de>
From:   Vitaly Wool <vitaly.wool@konsulko.com>
Date:   Thu, 14 Jan 2021 18:15:08 +0100
Message-ID: <CAM4kBBLqgh=ymq4pg6URB3OhjhRSH3O=4AEMRBuaC3Z0-hZ4Lg@mail.gmail.com>
Subject: Re: [PATCH] zsmalloc: do not use bit_spin_lock
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     "tiantao (H)" <tiantao6@huawei.com>,
        "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
        Shakeel Butt <shakeelb@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Mike Galbraith <efault@gmx.de>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, NitinGupta <ngupta@vflare.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "tiantao (H)" <tiantao6@hisilicon.com>
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On Thu, Jan 14, 2021 at 5:56 PM Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
>
> On 2021-01-14 17:29:37 [+0100], Vitaly Wool wrote:
> > On Thu, 14 Jan 2021, 17:18 Sebastian Andrzej Siewior,
> > <bigeasy@linutronix.de> wrote:
> > >
> > > On 2020-12-23 19:25:02 [+0100], Vitaly Wool wrote:
> > > > > write the following patch according to your idea, what do you think ?
> > > >
> > > > Yep, that is basically what I was thinking of. Some nitpicks below:
> > >
> > > Did this go somewhere? The thread just ends here on my end.
> > > Mike, is this patch fixing / helping your case in anyway?
> >
> > Please see
> > * https://marc.info/?l=linux-mm&m=160889419514019&w=2
> > * https://marc.info/?l=linux-mm&m=160889418114011&w=2
> > * https://marc.info/?l=linux-mm&m=160889448814057&w=2
>
> Thank you, that would be
>    1608894171-54174-1-git-send-email-tiantao6@hisilicon.com
>
> for b4 compatibility :)
>
> > Haven't had time to test these yet but seem to be alright.
>
> So zs_map_object() still disables preemption but the mutex part is
> avoided by the patch?

Basically, yes. Minchan was very clear that he didn't want to remove
that inter-function locking, so be it.
I wouldn't really advise to use zsmalloc with zswap because zsmalloc
has no support for reclaim, nevertheless I wouldn't like this
configuration to stop working for those who are already using it.

Would you or Mike be up for testing Tian Taos's patchset?

Best regards,
   Vitaly