On Tue 10-04-18 05:53:50, Matthew Wilcox wrote:
From: Matthew Wilcox mawilcox@microsoft.com
__GFP_ZERO requests that the object be initialised to all-zeroes, while the purpose of a constructor is to initialise an object to a particular pattern. We cannot do both. Add a warning to catch any users who mistakenly pass a __GFP_ZERO flag when allocating a slab with a constructor.
Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators") Signed-off-by: Matthew Wilcox mawilcox@microsoft.com Cc: stable@vger.kernel.org
mm/slab.c | 6 ++++-- mm/slob.c | 4 +++- mm/slub.c | 6 ++++-- 3 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c index 38d3f4fd17d7..8b2cb7db85db 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3313,8 +3313,10 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, local_irq_restore(save_flags); ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
- if (unlikely(flags & __GFP_ZERO) && ptr)
memset(ptr, 0, cachep->object_size);
- if (unlikely(flags & __GFP_ZERO) && ptr) {
if (!WARN_ON_ONCE(cachep->ctor))
memset(ptr, 0, cachep->object_size);
- }
slab_post_alloc_hook(cachep, flags, 1, &ptr); return ptr;
Why don't we need to cover this in slab_alloc and kmem_cache_alloc_bulk as well?
Other than that this patch makes sense to me.