From ae96e0cdc78c816b93f9617d65d144162692c09c Mon Sep 17 00:00:00 2001 From: Sumitra Sharma Date: Sat, 10 Jun 2023 10:57:12 -0700 Subject: [PATCH] lib: replace kmap() with kmap_local_page() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit kmap() has been deprecated in favor of the kmap_local_page() due to high cost, restricted mapping space, the overhead of a global lock for synchronization, and making the process sleep in the absence of free slots. kmap_local_page() is faster than kmap() and offers thread-local and CPU-local mappings, take pagefaults in a local kmap region and preserves preemption by saving the mappings of outgoing tasks and restoring those of the incoming one during a context switch. The mappings are kept thread local in the functions “dmirror_do_read” and “dmirror_do_write” in test_hmm.c Therefore, replace kmap() with kmap_local_page() and use mempcy_from/to_page() to avoid open coding kmap_local_page() + memcpy() + kunmap_local(). Remove the unused variable “tmp”. Link: https://lkml.kernel.org/r/20230610175712.GA348514@sumitra.com Signed-off-by: Sumitra Sharma Suggested-by: Fabio M. De Francesco Reviewed-by: Fabio M. De Francesco Reviewed-by: Ira Weiny Cc: Deepak R Varma Cc: Jérôme Glisse Signed-off-by: Andrew Morton --- lib/test_hmm.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 67e6f83fe0f8..717dcb830127 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -368,16 +368,13 @@ static int dmirror_do_read(struct dmirror *dmirror, unsigned long start, for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) { void *entry; struct page *page; - void *tmp; entry = xa_load(&dmirror->pt, pfn); page = xa_untag_pointer(entry); if (!page) return -ENOENT; - tmp = kmap(page); - memcpy(ptr, tmp, PAGE_SIZE); - kunmap(page); + memcpy_from_page(ptr, page, 0, PAGE_SIZE); ptr += PAGE_SIZE; bounce->cpages++; @@ -437,16 +434,13 @@ static int dmirror_do_write(struct dmirror *dmirror, unsigned long start, for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) { void *entry; struct page *page; - void *tmp; entry = xa_load(&dmirror->pt, pfn); page = xa_untag_pointer(entry); if (!page || xa_pointer_tag(entry) != DPT_XA_TAG_WRITE) return -ENOENT; - tmp = kmap(page); - memcpy(tmp, ptr, PAGE_SIZE); - kunmap(page); + memcpy_to_page(page, 0, ptr, PAGE_SIZE); ptr += PAGE_SIZE; bounce->cpages++;