The patch titled
Subject: mm/mempool: replace kmap_atomic() with kmap_local_page()
has been added to the -mm mm-unstable branch. Its filename is
mm-mempool-replace-kmap_atomic-with-kmap_local_page.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mempool-replace-kmap_atomic-with-kmap_local_page.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Fabio M. De Francesco" <fabio.maria.de.francesco@xxxxxxxxxxxxxxx>
Subject: mm/mempool: replace kmap_atomic() with kmap_local_page()
Date: Mon, 20 Nov 2023 15:26:31 +0100
kmap_atomic() has been deprecated in favor of kmap_local_page().
Therefore, replace kmap_atomic() with kmap_local_page().
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.
The code blocks between the mappings and un-mappings don't rely on the
above-mentioned side effects of kmap_atomic(), so that mere replacements
of the old API with the new one is all that they require (i.e., there is
no need to explicitly call pagefault_disable() and/or preempt_disable()).
Link: https://lkml.kernel.org/r/20231120142640.7077-1-fabio.maria.de.francesco@xxxxxxxxxxxxxxx
Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@xxxxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempool.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/mempool.c~mm-mempool-replace-kmap_atomic-with-kmap_local_page
+++ a/mm/mempool.c
@@ -64,10 +64,10 @@ static void check_element(mempool_t *poo
} else if (pool->free == mempool_free_pages) {
/* Mempools backed by page allocator */
int order = (int)(long)pool->pool_data;
- void *addr = kmap_atomic((struct page *)element);
+ void *addr = kmap_local_page((struct page *)element);
__check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
- kunmap_atomic(addr);
+ kunmap_local(addr);
}
}
@@ -89,10 +89,10 @@ static void poison_element(mempool_t *po
} else if (pool->alloc == mempool_alloc_pages) {
/* Mempools backed by page allocator */
int order = (int)(long)pool->pool_data;
- void *addr = kmap_atomic((struct page *)element);
+ void *addr = kmap_local_page((struct page *)element);
__poison_element(addr, 1UL << (PAGE_SHIFT + order));
- kunmap_atomic(addr);
+ kunmap_local(addr);
}
}
#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
_
Patches currently in -mm which might be from fabio.maria.de.francesco@xxxxxxxxxxxxxxx are
mm-memory-use-kmap_local_page-in-__wp_page_copy_user.patch
mm-mempool-replace-kmap_atomic-with-kmap_local_page.patch
mm-page_poison-replace-kmap_atomic-with-kmap_local_page.patch
