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From: Thorsten Leemhuis <regressions@leemhuis.info>
To: Song Liu <song@kernel.org>,
	bpf@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	kernel-team@fb.com, akpm@linux-foundation.org,
	rick.p.edgecombe@intel.com, hch@infradead.org,
	imbrenda@linux.ibm.com
Subject: Re: [PATCH bpf 0/2] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP
Date: Sat, 9 Apr 2022 13:43:49 +0200	[thread overview]
Message-ID: <8665439b-e82e-65b8-ddb6-da6a41d6f6da@leemhuis.info> (raw)
In-Reply-To: <20220408223443.3303509-1-song@kernel.org>

Hi, this is your Linux kernel regression tracker.

On 09.04.22 00:34, Song Liu wrote:
> Enabling HAVE_ARCH_HUGE_VMALLOC on x86_64 and use it for bpf_prog_pack has
> caused some issues [1], as many users of vmalloc are not yet ready to
> handle huge pages. To enable a more smooth transition to use huge page
> backed vmalloc memory, this set replaces VM_NO_HUGE_VMAP flag with an new
> opt-in flag, VM_ALLOW_HUGE_VMAP. More discussions about this topic can be
> found at [2].
> 
> Patch 1 removes VM_NO_HUGE_VMAP and adds VM_ALLOW_HUGE_VMAP.
> Patch 2 uses VM_ALLOW_HUGE_VMAP in bpf_prog_pack.
> 
> [1] https://lore.kernel.org/lkml/20220204185742.271030-1-song@kernel.org/
> [2] https://lore.kernel.org/linux-mm/20220330225642.1163897-1-song@kernel.org/

These patches apparently fix a regression (one that's mentioned in your
[2]) that I tracked. Hence in the next iteration of your patches could
you please instead add a 'Link:' tag pointing to the report for anyone
wanting to look into the backstory in the future, as explained in
'Documentation/process/submitting-patches.rst' and
'Documentation/process/5.Posting.rst'? E.g. like this:

"Link:
https://lore.kernel.org/netdev/14444103-d51b-0fb3-ee63-c3f182f0b546@molgen.mpg.de/"

Not totally sure, but I guess it needs a Fixes tag as well specifying
the change that cause this regression (that's "fac54e2bfb5b"). The
documents mentioned above explain this, too. A "Reported-by" might be
appropriate as well.

In anyone wonders why I care: there are internal and publicly used tools
and scripts out there that reply on proper "Link" tags. I don't known
how many, but there is at least one public tool I'm running that cares:
regzbot, my regression tracking bot, which I use to track Linux kernel
regressions and generate the regression reports sent to Linus. Proper
"Link:" tags allow the bot to automatically connect regression reports
with fixes being posted or applied to resolve the particular regression
-- which makes regression tracking a whole lot easier and feasible for
the Linux kernel. That's why it's a great help for me if people set
proper "Link" tags.

While at it, let me tell regzbot about this thread:
#regzbot ^backmonitor:
https://lore.kernel.org/netdev/14444103-d51b-0fb3-ee63-c3f182f0b546@molgen.mpg.de/

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

P.S.: As the Linux kernel's regression tracker I'm getting a lot of
reports on my table. I can only look briefly into most of them and lack
knowledge about most of the areas they concern. I thus unfortunately
will sometimes get things wrong or miss something important. I hope
that's not the case here; if you think it is, don't hesitate to tell me
in a public reply, it's in everyone's interest to set the public record
straight.

  parent reply	other threads:[~2022-04-09 11:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20220408223443.3303509-1-song@kernel.org>
     [not found] ` <20220408223443.3303509-2-song@kernel.org>
2022-04-09  5:28   ` [PATCH bpf 1/2] vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLOW_HUGE_VMAP Christoph Hellwig
2022-04-10  1:25     ` Song Liu
     [not found] ` <20220408223443.3303509-3-song@kernel.org>
2022-04-09  5:29   ` [PATCH bpf 2/2] bpf: use vmalloc with VM_ALLOW_HUGE_VMAP for bpf_prog_pack Christoph Hellwig
2022-04-10  1:34     ` Song Liu
2022-04-11  6:56       ` Christoph Hellwig
2022-04-11 22:18         ` Song Liu
2022-04-09 11:43 ` Thorsten Leemhuis [this message]
2022-04-10  1:36   ` [PATCH bpf 0/2] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP Song Liu

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