linux-kernel - Re: [PATCH] nvme: add cond_resched() to nvme_complete

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Message-ID: <ZFPJ7CYFEextnOqE@kbusch-mbp.dhcp.thefacebook.com>
Date:   Thu, 4 May 2023 09:06:20 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     Niklas Cassel <Niklas.Cassel@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "jiweisun126@....com" <jiweisun126@....com>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "axboe@...com" <axboe@...com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "ahuang12@...ovo.com" <ahuang12@...ovo.com>,
        "sunjw10@...ovo.com" <sunjw10@...ovo.com>
Subject: Re: [PATCH] nvme: add cond_resched() to nvme_complete_batch()

On Thu, May 04, 2023 at 10:12:46AM +0000, Niklas Cassel wrote:
> On Thu, May 04, 2023 at 11:39:53AM +0200, Niklas Cassel wrote:
> > 
> > Something is fishy here...
> > 
> > (Perhaps the maintainer did a git revert instead of applying the fix...
> > and accidentally squashed the revert with a proper commit...
> > But even that does not make sense, as there simply seems to be too many
> > lines changed in 2d55c16c0c54 ("dmapool: create/destroy cleanup") for that
> > to be the case...)
> 
> It seems like the additional lines in
> 2d55c16c0c54 ("dmapool: create/destroy cleanup") is explained by the
> maintainer (probably accidentally) reverting additional patches in that
> very same commit.
> 
> It seems like that commit reverted all changes to mm/dmapool.c since v6.3:

Spot on, thanks for confirming! Somehow a series revert was squahed into
the final patch. :(

We reached the same conclusion pretty late yesterday, so I'll wait for
Andrew to suggest how to proceed. I think we have to rebase whole series
with the correct final patch and resend the pull.
 
> $ git log --oneline 2d55c16c0c54325bf15286cfa6ba6c268036b9e4 --not v6.3 mm/dmapool.c 
> 2d55c16c0c54 dmapool: create/destroy cleanup
> a4de12a032fa dmapool: link blocks across pages
> 9d062a8a4c6d dmapool: don't memset on free twice
> 887aef615818 dmapool: simplify freeing
> 2591b516533b dmapool: consolidate page initialization
> 36d1a28921a4 dmapool: rearrange page alloc failure handling
> 52e7d5653979 dmapool: move debug code to own functions
> 19f504584038 dmapool: speedup DMAPOOL_DEBUG with init_on_alloc
> 347e4e44c0a9 dmapool: cleanup integer types
> 65216545436b dmapool: use sysfs_emit() instead of scnprintf()
> 7f796d141c07 dmapool: remove checks for dev == NULL
> 
> 
> $ git diff v6.3 2d55c16c0c54325bf15286cfa6ba6c268036b9e4 mm/dmapool.c
> <nothing>
> 
> 
> Should probably tell Andrew so that he has time to send out a new PR
> before the merge window closes. (I added him in To: .)
> 
> He should probably pick up this fix too:
> https://patchwork.kernel.org/project/linux-mm/patch/20230221165400.1595247-1-kbusch@meta.com/

Andrew actually squashed that fix into the original patch.