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De Francesco" To: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" , Ira Weiny Subject: [PATCH 1006/1007] mm/swapfile: Replace kmap_atomic() with kmap_local_page() Date: Mon, 27 Nov 2023 16:45:53 +0100 Message-ID: <20231127154601.585849-1-fabio.maria.de.francesco@linux.intel.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B86BB140003 X-Stat-Signature: hp46kdpamk7mb83woscwhzmpbh4wpp31 X-Rspam-User: X-HE-Tag: 1701099970-804458 X-HE-Meta: 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 PPFJ39zy LDRlQkYwdEuTzPKi3Hn0H2NqluYmv/DtlkDcbitlicvW09i4lz6294aLosFNBD/qE8cQExwOuMZG9Wgtd7+gCZxLpAGxHehmo9l5cU9mBDDgGHpEPn+l3izvPp83s7rhBwfg0n9mGz4a7AYMpnt7pSa8rBiN78jOYu8nD/QtJs9UTzR0swKQWenwxvg== 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 swapfile.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/swapfile.c, the blocks of code between the mappings and un-mappings do not depend on the above-mentioned side effects of kmap_aatomic(), 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/swapfile.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 4bc70f459164..8be70912e298 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1495,9 +1495,9 @@ int swp_swapcount(swp_entry_t entry) do { page = list_next_entry(page, lru); - map = kmap_atomic(page); + map = kmap_local_page(page); tmp_count = map[offset]; - kunmap_atomic(map); + kunmap_local(map); count += (tmp_count & ~COUNT_CONTINUED) * n; n *= (SWAP_CONT_MAX + 1); @@ -3477,9 +3477,9 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) if (!(count & COUNT_CONTINUED)) goto out_unlock_cont; - map = kmap_atomic(list_page) + offset; + map = kmap_local_page(list_page) + offset; count = *map; - kunmap_atomic(map); + kunmap_local(map); /* * If this continuation count now has some space in it, @@ -3529,7 +3529,7 @@ static bool swap_count_continued(struct swap_info_struct *si, spin_lock(&si->cont_lock); offset &= ~PAGE_MASK; page = list_next_entry(head, lru); - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; if (count == SWAP_MAP_MAX) /* initial increment from swap_map */ goto init_map; /* jump over SWAP_CONT_MAX checks */ @@ -3539,27 +3539,27 @@ static bool swap_count_continued(struct swap_info_struct *si, * Think of how you add 1 to 999 */ while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) { - kunmap_atomic(map); + kunmap_local(map); page = list_next_entry(page, lru); BUG_ON(page == head); - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; } if (*map == SWAP_CONT_MAX) { - kunmap_atomic(map); + kunmap_local(map); page = list_next_entry(page, lru); if (page == head) { ret = false; /* add count continuation */ goto out; } - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; init_map: *map = 0; /* we didn't zero the page */ } *map += 1; - kunmap_atomic(map); + kunmap_local(map); while ((page = list_prev_entry(page, lru)) != head) { - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; *map = COUNT_CONTINUED; - kunmap_atomic(map); + kunmap_local(map); } ret = true; /* incremented */ @@ -3569,21 +3569,21 @@ init_map: *map = 0; /* we didn't zero the page */ */ BUG_ON(count != COUNT_CONTINUED); while (*map == COUNT_CONTINUED) { - kunmap_atomic(map); + kunmap_local(map); page = list_next_entry(page, lru); BUG_ON(page == head); - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; } BUG_ON(*map == 0); *map -= 1; if (*map == 0) count = 0; - kunmap_atomic(map); + kunmap_local(map); while ((page = list_prev_entry(page, lru)) != head) { - map = kmap_atomic(page) + offset; + map = kmap_local_page(page) + offset; *map = SWAP_CONT_MAX | count; count = COUNT_CONTINUED; - kunmap_atomic(map); + kunmap_local(map); } ret = count == COUNT_CONTINUED; } -- 2.42.0