From 003ae2fb0b36803112f9b66cce8041afa5d46a83 Mon Sep 17 00:00:00 2001 From: "Fabio M. De Francesco" Date: Mon, 27 Nov 2023 16:55:21 +0100 Subject: [PATCH] mm/zswap: replace kmap_atomic() with kmap_local_page() 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()). Link: https://lkml.kernel.org/r/20231127160058.586446-1-fabio.maria.de.francesco@linux.intel.com Signed-off-by: Fabio M. De Francesco Reviewed-by: Nhat Pham Acked-by: Chris Li (Google) Cc: Ira Weiny Cc: Seth Jennings Cc: Dan Streetman Signed-off-by: Andrew Morton --- 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; }