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Tue, 10 Mar 2026 07:03:02 -0700 (PDT) MIME-Version: 1.0 References: <20260310060407.1133800-1-senozhatsky@chromium.org> In-Reply-To: From: Brian Geffon Date: Tue, 10 Mar 2026 10:02:25 -0400 X-Gm-Features: AaiRm505DSdRTNRL1G8h-GZEtlrvi5UA2vbcMF3uI1SjdIgSiG4KGr1my05BvOM 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-Queue-Id: 023441C0020 X-Rspamd-Server: rspam07 X-Stat-Signature: 9mihckhmoim1z4bc5wq6jnzmz8gmug84 X-Rspam-User: X-HE-Tag: 1773151383-602587 X-HE-Meta: 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 E+AaxCk+ aJsYQQBKKY4137qEi+o3mU6J2RpQgmg7d2BQUl/OWqyOi4P6IE6nGokjKE30ZfRC3xxEUzFct2ABbNGTs30Jro/JYWIFNkhQbwnkeIbqxGLXLnhKo2lW1ygHNWp07aklSbMzmWkk2kZZoBb7ETJhzQorjuKpxYylLCyv6vc4XS5aR1GUI1Q9rmPIjBp0kD7YC/Wtku+xEuGOYVBS5zz2rOKykO8wsJ3OBaxv0+I5/1oOm45X+8psTzAxPvd6mE12zjGOf8hApDJIljHgRvH7KXUzJyjZUa4jw1acOmFrn9y8JBfaEnIzLIC9H9DYHnWFhWhIqqHrszFMUpkmx4dgnBlBAHQ== 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 10:01=E2=80=AFAM Brian Geffon = wrote: > > 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()? disregard, that happens in __comp_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 attribut= e") > > 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_dr= v.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 dev= ice *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, &deflat= e_params); > > return ret ? ret : len; > > } > > -- > > 2.53.0.473.g4a7958ca14-goog > >