The patch titled
Subject: mm/zsmalloc: use memcpy_from/to_page whereever possible
has been added to the -mm mm-unstable branch. Its filename is
mm-zsmalloc-use-memcpy_from-to_page-whereever-possible.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zsmalloc-use-memcpy_from-to_page-whereever-possible.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: Pintu Kumar <quic_pintu@xxxxxxxxxxx>
Subject: mm/zsmalloc: use memcpy_from/to_page whereever possible
Date: Thu, 10 Oct 2024 23:21:43 +0530
As part of "zsmalloc: replace kmap_atomic with kmap_local_page" [1] we
replaced kmap/kunmap_atomic() with kmap_local_page()/kunmap_local().
But later it was found that some of the code could be replaced with
already available apis in highmem.h, such as
memcpy_from_page()/memcpy_to_page().
Also, update the comments with correct api naming.
[1] https://lkml.kernel.org/r/20241001175358.12970-1-quic_pintu@xxxxxxxxxxx
Link: https://lkml.kernel.org/r/20241010175143.27262-1-quic_pintu@xxxxxxxxxxx
Signed-off-by: Pintu Kumar <quic_pintu@xxxxxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Suggested-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Pintu Agarwal <pintu.ping@xxxxxxxxx>
Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)
--- a/mm/zsmalloc.c~mm-zsmalloc-use-memcpy_from-to_page-whereever-possible
+++ a/mm/zsmalloc.c
@@ -263,7 +263,7 @@ struct zspage {
struct mapping_area {
local_lock_t lock;
char *vm_buf; /* copy buffer for objects that span pages */
- char *vm_addr; /* address of kmap_atomic()'ed pages */
+ char *vm_addr; /* address of kmap_local_page()'ed pages */
enum zs_mapmode vm_mm; /* mapping mode */
};
@@ -1046,11 +1046,10 @@ static inline void __zs_cpu_down(struct
static void *__zs_map_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
- int sizes[2];
- void *addr;
+ size_t sizes[2];
char *buf = area->vm_buf;
- /* disable page faults to match kmap_atomic() return conditions */
+ /* disable page faults to match kmap_local_page() return conditions */
pagefault_disable();
/* no read fastpath */
@@ -1061,12 +1060,8 @@ static void *__zs_map_object(struct mapp
sizes[1] = size - sizes[0];
/* copy object to per-cpu buffer */
- addr = kmap_local_page(pages[0]);
- memcpy(buf, addr + off, sizes[0]);
- kunmap_local(addr);
- addr = kmap_local_page(pages[1]);
- memcpy(buf + sizes[0], addr, sizes[1]);
- kunmap_local(addr);
+ memcpy_from_page(buf, pages[0], off, sizes[0]);
+ memcpy_from_page(buf + sizes[0], pages[1], 0, sizes[1]);
out:
return area->vm_buf;
}
@@ -1074,8 +1069,7 @@ out:
static void __zs_unmap_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
- int sizes[2];
- void *addr;
+ size_t sizes[2];
char *buf;
/* no write fastpath */
@@ -1091,15 +1085,11 @@ static void __zs_unmap_object(struct map
sizes[1] = size - sizes[0];
/* copy per-cpu buffer to object */
- addr = kmap_local_page(pages[0]);
- memcpy(addr + off, buf, sizes[0]);
- kunmap_local(addr);
- addr = kmap_local_page(pages[1]);
- memcpy(addr, buf + sizes[0], sizes[1]);
- kunmap_local(addr);
+ memcpy_to_page(pages[0], off, buf, sizes[0]);
+ memcpy_to_page(pages[1], 0, buf + sizes[0], sizes[1]);
out:
- /* enable page faults to match kunmap_atomic() return conditions */
+ /* enable page faults to match kunmap_local() return conditions */
pagefault_enable();
}
@@ -1511,10 +1501,10 @@ static void zs_object_copy(struct size_c
d_size -= size;
/*
- * Calling kunmap_atomic(d_addr) is necessary. kunmap_atomic()
- * calls must occurs in reverse order of calls to kmap_atomic().
- * So, to call kunmap_atomic(s_addr) we should first call
- * kunmap_atomic(d_addr). For more details see
+ * Calling kunmap_local(d_addr) is necessary. kunmap_local()
+ * calls must occurs in reverse order of calls to kmap_local_page().
+ * So, to call kunmap_local(s_addr) we should first call
+ * kunmap_local(d_addr). For more details see
* Documentation/mm/highmem.rst.
*/
if (s_off >= PAGE_SIZE) {
_
Patches currently in -mm which might be from quic_pintu@xxxxxxxxxxx are
mm-cma-fix-useless-return-in-void-function.patch
zsmalloc-replace-kmap_atomic-with-kmap_local_page.patch
mm-zsmalloc-use-memcpy_from-to_page-whereever-possible.patch
