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authorSumitra Sharma <sumitraartsy@gmail.com>2023-06-10 10:57:12 -0700
committerAndrew Morton <akpm@linux-foundation.org>2023-08-18 10:18:50 -0700
commitae96e0cdc78c816b93f9617d65d144162692c09c (patch)
treef94355563a9cb7303fe1b6fb8ecc63dc41623b03 /lib
parentf58a2dd8d5d01b3ece13af7915745b8e7de20afe (diff)
lib: replace kmap() with kmap_local_page()
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 <sumitraartsy@gmail.com> Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Cc: Deepak R Varma <drv@mailo.com> Cc: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_hmm.c10
1 files 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++;