Merge tag 'slab-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab updates from Vlastimil Babka:

- Make kvmalloc() more suitable for callers that need it to succeed,
but without unnecessary overhead by reclaim and compaction to get a
physically contiguous allocation.

Instead fall back to vmalloc() more easily by default, unless
instructed by __GFP_RETRY_MAYFAIL to prefer kmalloc() harder. This
should allow the removal of a xfs-specific workaround (Michal Hocko)

- Remove potentially excessive warnings due to memory pressure when
allocating structures for per-object allocation profiling metadata
(Usama Arif)

* tag 'slab-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm: slub: only warn once when allocating slab obj extensions fails
mm: kvmalloc: make kmalloc fast path real fast path

mm/slub.c

···
 
 	slab = virt_to_slab(p);
 	if (!slab_obj_exts(slab) &&
-	    WARN(alloc_slab_obj_exts(slab, s, flags, false),
-		 "%s, %s: Failed to create slab extension vector!\n",
-		 __func__, s->name))
+	    alloc_slab_obj_exts(slab, s, flags, false)) {
+		pr_warn_once("%s, %s: Failed to create slab extension vector!\n",
+			     __func__, s->name);
 		return NULL;
+	}
 
 	return slab_obj_exts(slab) + obj_to_index(s, slab, p);
 }
···
 	 * We want to attempt a large physically contiguous block first because
 	 * it is less likely to fragment multiple larger blocks and therefore
 	 * contribute to a long term fragmentation less than vmalloc fallback.
-	 * However make sure that larger requests are not too disruptive - no
-	 * OOM killer and no allocation failure warnings as we have a fallback.
+	 * However make sure that larger requests are not too disruptive - i.e.
+	 * do not direct reclaim unless physically continuous memory is preferred
+	 * (__GFP_RETRY_MAYFAIL mode). We still kick in kswapd/kcompactd to
+	 * start working in the background
 	 */
 	if (size > PAGE_SIZE) {
 		flags |= __GFP_NOWARN;
 
 		if (!(flags & __GFP_RETRY_MAYFAIL))
-			flags |= __GFP_NORETRY;
+			flags &= ~__GFP_DIRECT_RECLAIM;
 
 		/* nofail semantic is implemented by the vmalloc fallback */
 		flags &= ~__GFP_NOFAIL;