LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Suren Baghdasaryan <surenb@google.com>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>, Michal Hocko <mhocko@suse.com>,
	David Rientjes <rientjes@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Roman Gushchin <guro@fb.com>, Rik van Riel <riel@surriel.com>,
	Minchan Kim <minchan@kernel.org>,
	Christian Brauner <christian@brauner.io>,
	Christoph Hellwig <hch@infradead.org>,
	Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>,
	Shakeel Butt <shakeelb@google.com>,
	Andy Lutomirski <luto@kernel.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Florian Weimer <fweimer@redhat.com>,
	Jan Engelhardt <jengelh@inai.de>,
	Tim Murray <timmurray@google.com>,
	Linux API <linux-api@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kernel-team <kernel-team@android.com>
Subject: Re: [PATCH v2 1/3] mm, oom: move task_will_free_mem up in the file to be used in process_mrelease
Date: Wed, 21 Jul 2021 08:33:56 -0700	[thread overview]
Message-ID: <CAJuCfpEB994Xj3FcmzyH1p3yOdLVf6EwZaGaRj7NJi_c9hbsRQ@mail.gmail.com> (raw)
In-Reply-To: <ba763ed3-9ad1-9502-1ffc-3175446570d1@redhat.com>

On Wed, Jul 21, 2021 at 12:30 AM David Hildenbrand <david@redhat.com> wrote:
>
> On 21.07.21 01:07, Andrew Morton wrote:
> > On Tue, 20 Jul 2021 14:43:52 +0200 David Hildenbrand <david@redhat.com> wrote:
> >
> >> On 18.07.21 23:41, Suren Baghdasaryan wrote:
> >>> process_mrelease needs to be added in the CONFIG_MMU-dependent block which
> >>> comes before __task_will_free_mem and task_will_free_mem. Move these
> >>> functions before this block so that new process_mrelease syscall can use
> >>> them.
> >>>
> >>> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> >>> ---
> >>> changes in v2:
> >>> - Fixed build error when CONFIG_MMU=n, reported by kernel test robot. This
> >>> required moving task_will_free_mem implemented in the first patch
> >>> - Renamed process_reap to process_mrelease, per majority of votes
> >>> - Replaced "dying process" with "process which was sent a SIGKILL signal" in
> >>> the manual page text, per Florian Weimer
> >>> - Added ERRORS section in the manual page text
> >>> - Resolved conflicts in syscall numbers caused by the new memfd_secret syscall
> >>> - Separated boilerplate code wiring-up the new syscall into a separate patch
> >>> to facilitate the review process
> >>>
> >>>    mm/oom_kill.c | 150 +++++++++++++++++++++++++-------------------------
> >>>    1 file changed, 75 insertions(+), 75 deletions(-)
> >>
> >> TBH, I really dislike this move as it makes git blame a lot harder with
> >> any real benefit.
> >>
> >> Can't you just use prototypes to avoid the move for now in patch #2?
> >>
> >> static bool task_will_free_mem(struct task_struct *task);
> >
> > This change makes the code better - it's silly to be adding forward
> > declarations just because the functions are in the wrong place.
>
> I'd really love to learn what "better" here means and if it's rather
> subjective. When it comes to navigating the code, we do have established
> tools for that (ctags), and personally I couldn't care less where
> exactly in a file the code is located.
>
> Sure, ending up with a forward-declaration for every function might not
> be what we want ;)
>
> >
> > If that messes up git-blame then let's come up with better tooling
> > rather than suffering poorer kernel code because the tools aren't doing
> > what we want of them.  Surely?
>
> I don't agree that what we get is "poorer kernel code" in this very
> instance; I can understand that we avoid forward-declarations when
> moving smallish functions. But moving two functions with 75 LOC is a bit
> too much for my taste at least -- speaking as someone who cares about
> easy backports and git-blame.

There is a third alternative here to have process_mrelease() at the
end of the file with its own #ifdef CONFIG_MMU block, maybe even
embedded in the function like this:

 int process_mrelease(int pidfd, unsigned int flags)
{
#ifdef CONFIG_MMU
        ...
#else
        return ENOSYS;
#endif
}

This would not require moving other functions.
Would that be better than the current approach or the forward declaration?

>
> Anyhow, just my 2 cents.
>
> --
> Thanks,
>
> David / dhildenb
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
>

  reply	other threads:[~2021-07-21 15:34 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-18 21:41 Suren Baghdasaryan
2021-07-18 21:41 ` [PATCH v2 2/3] mm: introduce process_mrelease system call Suren Baghdasaryan
2021-07-21  8:02   ` David Hildenbrand
2021-07-21 15:43     ` Suren Baghdasaryan
2021-07-21 22:59       ` Suren Baghdasaryan
2021-07-22  7:45         ` David Hildenbrand
2021-07-18 21:41 ` [PATCH v2 3/3] mm: wire up syscall process_mrelease Suren Baghdasaryan
2021-07-20 12:43 ` [PATCH v2 1/3] mm, oom: move task_will_free_mem up in the file to be used in process_mrelease David Hildenbrand
2021-07-20 16:18   ` Suren Baghdasaryan
2021-07-20 23:07   ` Andrew Morton
2021-07-21  7:30     ` David Hildenbrand
2021-07-21 15:33       ` Suren Baghdasaryan [this message]
2021-07-21 16:12         ` David Hildenbrand
2021-07-21 20:19           ` Suren Baghdasaryan
2021-07-21 20:50             ` Andrew Morton
2021-07-21 20:59               ` Suren Baghdasaryan
2021-07-23  1:15                 ` Suren Baghdasaryan

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAJuCfpEB994Xj3FcmzyH1p3yOdLVf6EwZaGaRj7NJi_c9hbsRQ@mail.gmail.com \
    --to=surenb@google.com \
    --cc=akpm@linux-foundation.org \
    --cc=christian.brauner@ubuntu.com \
    --cc=christian@brauner.io \
    --cc=david@redhat.com \
    --cc=fweimer@redhat.com \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=hch@infradead.org \
    --cc=jannh@google.com \
    --cc=jengelh@inai.de \
    --cc=kernel-team@android.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=luto@kernel.org \
    --cc=mhocko@kernel.org \
    --cc=mhocko@suse.com \
    --cc=minchan@kernel.org \
    --cc=oleg@redhat.com \
    --cc=riel@surriel.com \
    --cc=rientjes@google.com \
    --cc=shakeelb@google.com \
    --cc=timmurray@google.com \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH v2 1/3] mm, oom: move task_will_free_mem up in the file to be used in process_mrelease' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).