On Fri 17-04-20 00:09:35, Bernard Zhao wrote: > kmalloc size should never exceed KMALLOC_MAX_SIZE. > kmalloc_index realise if size is exceed KMALLOC_MAX_SIZE, e.g 64M, > kmalloc_index just return index 26, but never check with OS`s max > kmalloc config KMALLOC_MAX_SIZE. This index`s kmalloc caches maybe > not create in function create_kmalloc_caches. > We can throw an warninginfo in kmalloc at the beginning, instead of > being guaranteed by the buddy alloc behind. I am sorry but I do not follow. What does this patch optimizes? AFAICS, it adds a branch for everybody for something that is highly unlikely usage. Btw. we already do handle those impossible cases. We could argue that BUG() is a bit harsh reaction but a lack of reports suggests this is not a real problem in fact. So what exactly do you want to achieve here? > Signed-off-by: Bernard Zhao <bernard@xxxxxxxx> > --- > include/linux/slab.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 6d45488..59b60d2 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -351,6 +351,10 @@ static __always_inline unsigned int kmalloc_index(size_t size) > if (!size) > return 0; > > + /* size should never exceed KMALLOC_MAX_SIZE. */ > + if (size > KMALLOC_MAX_SIZE) > + WARN(1, "size exceed max kmalloc size!\n"); > + > if (size <= KMALLOC_MIN_SIZE) > return KMALLOC_SHIFT_LOW; > > -- > 2.7.4 > -- Michal Hocko SUSE Labs
