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De Francesco" Cc: Seth Jennings , Dan Streetman , Vitaly Wool , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ira Weiny Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 9B6701C0069 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: k4hphemy4sp35bxcyc5ggm7mrh6iwjy5 X-HE-Tag: 1701108470-468714 X-HE-Meta: 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 IwB9/k5D 590/AJ+hbF3XdtBSYQ5MgKn8RRaHPZcxK5ZOO/ar4VPlZ7cD0tLD2xV8lG84k4BR2uj9B80UtbO75UfVwKnPG2UIetx/oEzMIgyAv6XnlprvT0GjMYFNkUOy1DfEr2FD7CAsskJTaQ84EDhtjSarBSdU2dZsh67e40lu20z3ZoUZxI1n3pJkQX24zd5opkrhJ/ItT0ql43SnAqU2Ly44E0rx/DEVs68qyyVytxfHz+yWV8040QAybUqa4oAvntbvQPmvDwRfcwDtorViwqKHzvHbPOetSbR9apevG2X0yKsGRyMZZw5+xRi/3hHHL8cZdOTeNKpOtfcaPbaQ04qoK6bOsZLIrXC+M/pbA4GOEj4ndzBIW006GBNs6faG/1GKjXjLswXvtd46dlWOzQyWGhy+QsMjV3VH2QFfQEYI0NGUM6sIcFrpnkt4XlDk7JOB4huG6 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 27, 2023 at 8:03=E2=80=AFAM Fabio M. De Francesco wrote: > > kmap_atomic() has been deprecated in favor of kmap_local_page(). > > Therefore, replace kmap_atomic() with kmap_local_page() in > zswap.c. > > kmap_atomic() is implemented like a kmap_local_page() which also > disables page-faults and preemption (the latter only in !PREEMPT_RT > kernels). The kernel virtual addresses returned by these two API are > only valid in the context of the callers (i.e., they cannot be handed to > other threads). > > With kmap_local_page() the mappings are per thread and CPU local like > in kmap_atomic(); however, they can handle page-faults and can be called > from any context (including interrupts). The tasks that call > kmap_local_page() can be preempted and, when they are scheduled to run > again, the kernel virtual addresses are restored and are still valid. > > In mm/zswap.c, the blocks of code between the mappings and un-mappings > do not depend on the above-mentioned side effects of kmap_atomic(), so > that the mere replacements of the old API with the new one is all that is > required (i.e., there is no need to explicitly call pagefault_disable() > and/or preempt_disable()). > > Cc: Ira Weiny > Signed-off-by: Fabio M. De Francesco > --- > mm/zswap.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/mm/zswap.c b/mm/zswap.c > index 74411dfdad92..699c6ee11222 100644 > --- a/mm/zswap.c > +++ b/mm/zswap.c > @@ -1267,16 +1267,16 @@ bool zswap_store(struct folio *folio) > } > > if (zswap_same_filled_pages_enabled) { > - src =3D kmap_atomic(page); > + src =3D kmap_local_page(page); > if (zswap_is_page_same_filled(src, &value)) { > - kunmap_atomic(src); > + kunmap_local(src); > entry->swpentry =3D swp_entry(type, offset); > entry->length =3D 0; > entry->value =3D value; > atomic_inc(&zswap_same_filled_pages); > goto insert_entry; > } > - kunmap_atomic(src); > + kunmap_local(src); > } > > if (!zswap_non_same_filled_pages_enabled) > @@ -1422,9 +1422,9 @@ bool zswap_load(struct folio *folio) > spin_unlock(&tree->lock); > > if (!entry->length) { > - dst =3D kmap_atomic(page); > + dst =3D kmap_local_page(page); > zswap_fill_page(dst, entry->value); > - kunmap_atomic(dst); > + kunmap_local(dst); > ret =3D true; > goto stats; > } > -- > 2.42.0 > > Probably worth running a couple rounds of stress tests, but otherwise LGTM. FWIW, I've wanted to do this ever since I worked on the storing-uncompressed-pages patch. Reviewed-by: Nhat Pham