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De Francesco" To: Seth Jennings , Dan Streetman , Vitaly Wool , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" , Ira Weiny Subject: [PATCH] mm/zswap: Replace kmap_atomic() with kmap_local_page() Date: Mon, 27 Nov 2023 16:55:21 +0100 Message-ID: <20231127160058.586446-1-fabio.maria.de.francesco@linux.intel.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 208BE4007E X-Stat-Signature: bh39mdfx3nfxdb9d1yjf6ucoxohoey3u X-HE-Tag: 1701100904-233233 X-HE-Meta: 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 qeULF8LL 2xWCOcw7WkOIb4tXiHsHgKI50Av5wHLwPJc4iidbp+1PdEGMuPag1syNi48oe4E1nogGqGouVyNLoAXHlf29ocNz6CElidUAtX+a6Zd4oWPIhmhwlVG6uxH/aIciPo4isZa+DedxZn+pWHQCqRbB6oJ4+Ci52D7V9Yzu9OHtUMqhpIu+86YRE+5yEKQ== 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: 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 = kmap_atomic(page); + src = kmap_local_page(page); if (zswap_is_page_same_filled(src, &value)) { - kunmap_atomic(src); + kunmap_local(src); entry->swpentry = swp_entry(type, offset); entry->length = 0; entry->value = 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 = kmap_atomic(page); + dst = kmap_local_page(page); zswap_fill_page(dst, entry->value); - kunmap_atomic(dst); + kunmap_local(dst); ret = true; goto stats; } -- 2.42.0