From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Jens Axboe <axboe@kernel.dk>, Dongyun Liu <dongyun.liu3@gmail.com>
Cc: minchan@kernel.org, senozhatsky@chromium.org,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
lincheng.yang@transsion.com, jiajun.ling@transsion.com,
ldys2014@foxmail.com, Dongyun Liu <dongyun.liu@transsion.com>
Subject: Re: [PATCH] zram: Using GFP_ATOMIC instead of GFP_KERNEL to allocate bitmap memory in backing_dev_store
Date: Sat, 2 Dec 2023 00:28:22 +0900 [thread overview]
Message-ID: <20231201152822.GA404241@google.com> (raw)
In-Reply-To: <b26ab8d0-c719-4bf6-b909-26f4c014574b@kernel.dk>
On (23/12/01 07:19), Jens Axboe wrote:
> >> IOW, you have a slew of GFP_KERNEL allocations in there, and you
> >> probably just patched the largest one. But the core issue remains.
> >>
> >> The whole handling of backing_dev_store() looks pretty broken.
> >>
> >
> > Indeed, this patch only solves the biggest problem and does not
> > fundamentally solve it, because there are many processes for holding
> > zram->init_lock before allocation memory in backing_dev_store that
> > need to be fully modified, and I did not consider it thoroughly.
> > Obviously, a larger and better patch is needed to eliminate this risk,
> > but it is currently not necessary.
>
> You agree that it doesn't fix the issue, it just happens to fix the one
> that you hit. And then you jump to the conclusion that this is all
> that's needed to fix it. Ehm, confused?
Yeah.
zram is very sensitive to memory - zsmalloc pool needs physical pages
(allocated on demand) to keep data written to zram. zram probably simply
should not be used on systems under such heavy memory pressure. Throwing
GPF_ATOMICs at zram isn't going to fix anything.
Jens, you said that zram's backing device handling is broken. Got a minute
to elaborate?
next prev parent reply other threads:[~2023-12-01 15:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-30 15:20 [PATCH] zram: Using GFP_ATOMIC instead of GFP_KERNEL to allocate bitmap memory in backing_dev_store Dongyun Liu
2023-11-30 15:37 ` Jens Axboe
2023-12-01 6:51 ` Dongyun Liu
2023-12-01 14:19 ` Jens Axboe
2023-12-01 15:28 ` Sergey Senozhatsky [this message]
2023-12-02 13:54 ` Dongyun Liu
2023-12-01 15:39 ` Sergey Senozhatsky
2023-12-02 15:50 ` Dongyun Liu
2023-12-03 1:23 ` Sergey Senozhatsky
2023-12-03 14:45 ` Dongyun Liu
2023-12-01 18:41 ` Minchan Kim
2023-12-06 8:08 kernel test robot
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=20231201152822.GA404241@google.com \
--to=senozhatsky@chromium.org \
--cc=axboe@kernel.dk \
--cc=dongyun.liu3@gmail.com \
--cc=dongyun.liu@transsion.com \
--cc=jiajun.ling@transsion.com \
--cc=ldys2014@foxmail.com \
--cc=lincheng.yang@transsion.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=minchan@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.