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mm/zsmalloc: use memcpy_from/to_page whereever possible

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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@quicinc.com

Link: https://lkml.kernel.org/r/20241010175143.27262-1-quic_pintu@quicinc.com
Signed-off-by: Pintu Kumar <quic_pintu@quicinc.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Joe Perches <joe@perches.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pintu Agarwal <pintu.ping@gmail.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Pintu Kumar 2024-10-10 23:21:43 +05:30 committed by Andrew Morton
parent 91d0ec8347
commit e664c2cd98
1 changed files with 13 additions and 23 deletions
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36
mm/zsmalloc.c
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@ -263,7 +263,7 @@ struct zspage {
struct mapping_area { struct mapping_area {
local_lock_t lock; local_lock_t lock;
char *vm_buf; /* copy buffer for objects that span pages */ 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 */ enum zs_mapmode vm_mm; /* mapping mode */
}; };
@ -1046,11 +1046,10 @@ static inline void __zs_cpu_down(struct mapping_area *area)
static void *__zs_map_object(struct mapping_area *area, static void *__zs_map_object(struct mapping_area *area,
struct page *pages[2], int off, int size) struct page *pages[2], int off, int size)
{ {
int sizes[2]; size_t sizes[2];
void *addr;
char *buf = area->vm_buf; 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(); pagefault_disable();
/* no read fastpath */ /* no read fastpath */
@ -1061,12 +1060,8 @@ static void *__zs_map_object(struct mapping_area *area,
sizes[1] = size - sizes[0]; sizes[1] = size - sizes[0];
/* copy object to per-cpu buffer */ /* copy object to per-cpu buffer */
addr = kmap_local_page(pages[0]); memcpy_from_page(buf, pages[0], off, sizes[0]);
memcpy(buf, addr + off, sizes[0]); memcpy_from_page(buf + sizes[0], pages[1], 0, sizes[1]);
kunmap_local(addr);
addr = kmap_local_page(pages[1]);
memcpy(buf + sizes[0], addr, sizes[1]);
kunmap_local(addr);
out: out:
return area->vm_buf; return area->vm_buf;
} }
@ -1074,8 +1069,7 @@ out:
static void __zs_unmap_object(struct mapping_area *area, static void __zs_unmap_object(struct mapping_area *area,
struct page *pages[2], int off, int size) struct page *pages[2], int off, int size)
{ {
int sizes[2]; size_t sizes[2];
void *addr;
char *buf; char *buf;
/* no write fastpath */ /* no write fastpath */
@ -1091,15 +1085,11 @@ static void __zs_unmap_object(struct mapping_area *area,
sizes[1] = size - sizes[0]; sizes[1] = size - sizes[0];
/* copy per-cpu buffer to object */ /* copy per-cpu buffer to object */
addr = kmap_local_page(pages[0]); memcpy_to_page(pages[0], off, buf, sizes[0]);
memcpy(addr + off, buf, sizes[0]); memcpy_to_page(pages[1], 0, buf + sizes[0], sizes[1]);
kunmap_local(addr);
addr = kmap_local_page(pages[1]);
memcpy(addr, buf + sizes[0], sizes[1]);
kunmap_local(addr);
out: out:
/* enable page faults to match kunmap_atomic() return conditions */ /* enable page faults to match kunmap_local() return conditions */
pagefault_enable(); pagefault_enable();
} }
@ -1511,10 +1501,10 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
d_size -= size; d_size -= size;
/* /*
* Calling kunmap_atomic(d_addr) is necessary. kunmap_atomic() * Calling kunmap_local(d_addr) is necessary. kunmap_local()
* calls must occurs in reverse order of calls to kmap_atomic(). * calls must occurs in reverse order of calls to kmap_local_page().
* So, to call kunmap_atomic(s_addr) we should first call * So, to call kunmap_local(s_addr) we should first call
* kunmap_atomic(d_addr). For more details see * kunmap_local(d_addr). For more details see
* Documentation/mm/highmem.rst. * Documentation/mm/highmem.rst.
*/ */
if (s_off >= PAGE_SIZE) { if (s_off >= PAGE_SIZE) {