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Tue, 10 Mar 2026 07:02:03 -0700 (PDT) MIME-Version: 1.0 References: <20260310060407.1133800-1-senozhatsky@chromium.org> In-Reply-To: <20260310060407.1133800-1-senozhatsky@chromium.org> From: Brian Geffon Date: Tue, 10 Mar 2026 10:01:27 -0400 X-Gm-Features: AaiRm53oXK-y_X72MbDBnlVPnKuN7PrK0OkebVAEP3R7Ae_eXpwB4ioa6ZhtZZQ Message-ID: Subject: Re: [PATCH] zram: do not permit params change after init To: Sergey Senozhatsky Cc: Andrew Morton , Minchan Kim , linux-block@vger.kernel.org, linux-mm@kvack.org, gao xu Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B91751C0022 X-Stat-Signature: 6zzn51w9f4ay3caujcf436m1mfe5urgq X-Rspam-User: X-HE-Tag: 1773151325-352469 X-HE-Meta: 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 jfu3/dBy JTyjZG9bXYQI5d46X5jiLTbC/hsjeFoCHgO7wp70N0rvQ0Vb5T4cNNqwPmV2h7zGEtDYB2lKbZnExAnfvhrMAMdyQ/gHnRC3JE9JHIU9eOk9e5Tga+S9lktePtoW59BMNYvMwYGhZMFcnNHKCuwzPCJdKvj8R0E5CvkMl0LTTJyoIxhxyhHmOcv7+IoWKCev2QPr0Ct6yKG8TrnMCgNFzlO14NF/xQQX2lGvGOiBZYeQc1yNIzDjahwGcZcTc3JVeJaKXpj9YcKJ+XTzSRRaX+FS+X044stw1vKQVpDrXYhG6/6knQujDIfm+znr1rDM9WorN3ORT35ys2JeaMdPCKxIPpA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 10, 2026 at 2:04=E2=80=AFAM Sergey Senozhatsky wrote: > > First, algorithm_params_store(), like any sysfs handler, > should grab device init lock. > > Second, like any write() sysfs handler, it should grab > device init lock in exclusive mode. comp_algorithm_store() and recomp_algorithm_store()? > > Third, it should not permit change of algos' parameters > after device init, as this doesn't make sense - we cannot > compress with one C/D dict and then just change C/D dict > to a different one, for example. > > Fixes: 4eac932103a5d ("zram: introduce algorithm_params device attribute"= ) > Cc: gao xu > Signed-off-by: Sergey Senozhatsky Acked-by: Brian Geffon > --- > drivers/block/zram/zram_drv.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.= c > index c41e1257243f..7551c5e664a9 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -1769,6 +1769,10 @@ static ssize_t algorithm_params_store(struct devic= e *dev, > if (prio < ZRAM_PRIMARY_COMP || prio >=3D ZRAM_MAX_COMPS) > return -EINVAL; > > + guard(rwsem_write)(&zram->dev_lock); > + if (init_done(zram)) > + return -EBUSY; > + > ret =3D comp_params_store(zram, prio, level, dict_path, &deflate_= params); > return ret ? ret : len; > } > -- > 2.53.0.473.g4a7958ca14-goog >