On 3/2/25 14:30, Harry Yoo wrote:
> On Sat, Mar 01, 2025 at 04:37:20PM +0800, Ye Bin wrote:
>> From: Ye Bin <yebin10@xxxxxxxxxx>
>>
>> If 'n' or 'size' isn't builtin constant just call __kmalloc_noprof()
>> in kmalloc_array_noprof().
>>
>> Fixes: 7bd230a26648 ("mm/slab: enable slab allocation tagging for kmalloc and friends")
>> Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
>> ---
>> include/linux/slab.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/linux/slab.h b/include/linux/slab.h
>> index 3b03b31831a9..0edb8363fc4f 100644
>> --- a/include/linux/slab.h
>> +++ b/include/linux/slab.h
>> @@ -947,7 +947,7 @@ static inline __alloc_size(1, 2) void *kmalloc_array_noprof(size_t n, size_t siz
>> return NULL;
>> if (__builtin_constant_p(n) && __builtin_constant_p(size))
>> return kmalloc_noprof(bytes, flags);
>> - return kmalloc_noprof(bytes, flags);
>> + return __kmalloc_noprof(bytes, flags);
>
> Can we simply call kmalloc_noprof(bytes, flags) once instead?
>
> The compiler should know 'bytes' is a constant if both 'n' and 'size' are
> constants.
Right, applied like this, hope it's ok?
commit a6553ee4b00ba4b1466a81fb00fa4679b7ce5339 (HEAD -> slab/for-6.15/fixes-cleanups)
Author: Ye Bin <yebin10@xxxxxxxxxx>
Date: Sat Mar 1 16:37:20 2025 +0800
mm/slab: call kmalloc_noprof() unconditionally in kmalloc_array_noprof()
If 'n' or 'size' isn't builtin constant, we used to call __kmalloc()
before commit 7bd230a26648 ("mm/slab: enable slab allocation tagging for
kmalloc and friends"), which inadvertedly changed both paths to
kmalloc_noprof().
As Harry Yoo points out we can just call kmalloc_noprof()
unconditionally. If the compiler knows n and size are constants it
doesn't guarantee that bytes will be also seen as constant, and that is
the important test in kmalloc_noprof() here, so we can just defer to it
always.
[ vbabka@xxxxxxx: change as Harry suggested and adjust commit log ]
Fixes: 7bd230a26648 ("mm/slab: enable slab allocation tagging for kmalloc and friends")
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 09eedaecf120..ab05a143d09a 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -941,8 +941,6 @@ static inline __alloc_size(1, 2) void *kmalloc_array_noprof(size_t n, size_t siz
if (unlikely(check_mul_overflow(n, size, &bytes)))
return NULL;
- if (__builtin_constant_p(n) && __builtin_constant_p(size))
- return kmalloc_noprof(bytes, flags);
return kmalloc_noprof(bytes, flags);
}
#define kmalloc_array(...) alloc_hooks(kmalloc_array_noprof(__VA_ARGS__))
