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authorFabio De Francesco <fabio.maria.de.francesco@linux.intel.com>2023-11-20 15:15:27 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-12-11 01:51:49 +0100
commit2f7537620f383de121eaeb25f3e073a27831d086 (patch)
treef0a44ad4d4a190512bcac29138d8accbfb35b9f5 /mm/util.c
parentmm: use vmem_altmap code without CONFIG_ZONE_DEVICE (diff)
downloadlinux-2f7537620f383de121eaeb25f3e073a27831d086.tar.xz
linux-2f7537620f383de121eaeb25f3e073a27831d086.zip
mm/util: use kmap_local_page() in memcmp_pages()
kmap_atomic() has been deprecated in favor of kmap_local_page(). Therefore, replace kmap_atomic() with kmap_local_page() in memcmp_pages(). 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 memcmp_pages(), the block of code between the mapping and un-mapping does not depend on the above-mentioned side effects of kmap_aatomic(), so that 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()). Link: https://lkml.kernel.org/r/20231120141554.6612-1-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/util.c')
-rw-r--r--mm/util.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/util.c b/mm/util.c
index 744b4d7e3fae..5a6a9802583b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1047,11 +1047,11 @@ int __weak memcmp_pages(struct page *page1, struct page *page2)
char *addr1, *addr2;
int ret;
- addr1 = kmap_atomic(page1);
- addr2 = kmap_atomic(page2);
+ addr1 = kmap_local_page(page1);
+ addr2 = kmap_local_page(page2);
ret = memcmp(addr1, addr2, PAGE_SIZE);
- kunmap_atomic(addr2);
- kunmap_atomic(addr1);
+ kunmap_local(addr2);
+ kunmap_local(addr1);
return ret;
}