[merged mm-stable] mm-kvmalloc-add-non-blocking-support-for-vmalloc.patch removed from -mm tree

[merged mm-stable] mm-kvmalloc-add-non-blocking-support-for-vmalloc.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm: kvmalloc: add non-blocking support for vmalloc
has been removed from the -mm tree.  Its filename was
     mm-kvmalloc-add-non-blocking-support-for-vmalloc.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Subject: mm: kvmalloc: add non-blocking support for vmalloc
Date: Tue, 7 Oct 2025 14:20:35 +0200

Extend __kvmalloc_node_noprof() to handle non-blocking GFP flags
(GFP_NOWAIT and GFP_ATOMIC).  Previously such flags were rejected,
returning NULL.  With this change:

- kvmalloc() can fall back to vmalloc() if non-blocking contexts;
- for non-blocking allocations the VM_ALLOW_HUGE_VMAP option is
  disabled, since the huge mapping path still contains might_sleep();
- documentation update to reflect that GFP_NOWAIT and GFP_ATOMIC
  are now supported.

Link: https://lkml.kernel.org/r/20251007122035.56347-11-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/slub.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

--- a/mm/slub.c~mm-kvmalloc-add-non-blocking-support-for-vmalloc
+++ a/mm/slub.c
@@ -7090,7 +7090,7 @@ static gfp_t kmalloc_gfp_adjust(gfp_t fl
  * Uses kmalloc to get the memory but if the allocation fails then falls back
  * to the vmalloc allocator. Use kvfree for freeing the memory.
  *
- * GFP_NOWAIT and GFP_ATOMIC are not supported, neither is the __GFP_NORETRY modifier.
+ * GFP_NOWAIT and GFP_ATOMIC are supported, the __GFP_NORETRY modifier is not.
  * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
  * preferable to the vmalloc fallback, due to visible performance drawbacks.
  *
@@ -7099,6 +7099,7 @@ static gfp_t kmalloc_gfp_adjust(gfp_t fl
 void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), unsigned long align,
 			     gfp_t flags, int node)
 {
+	bool allow_block;
 	void *ret;
 
 	/*
@@ -7111,10 +7112,6 @@ void *__kvmalloc_node_noprof(DECL_BUCKET
 	if (ret || size <= PAGE_SIZE)
 		return ret;
 
-	/* non-sleeping allocations are not supported by vmalloc */
-	if (!gfpflags_allow_blocking(flags))
-		return NULL;
-
 	/* Don't even allow crazy sizes */
 	if (unlikely(size > INT_MAX)) {
 		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
@@ -7122,13 +7119,23 @@ void *__kvmalloc_node_noprof(DECL_BUCKET
 	}
 
 	/*
+	 * For non-blocking the VM_ALLOW_HUGE_VMAP is not used
+	 * because the huge-mapping path in vmalloc contains at
+	 * least one might_sleep() call.
+	 *
+	 * TODO: Revise huge-mapping path to support non-blocking
+	 * flags.
+	 */
+	allow_block = gfpflags_allow_blocking(flags);
+
+	/*
 	 * kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
 	 * since the callers already cannot assume anything
 	 * about the resulting pointer, and cannot play
 	 * protection games.
 	 */
 	return __vmalloc_node_range_noprof(size, align, VMALLOC_START, VMALLOC_END,
-			flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
+			flags, PAGE_KERNEL, allow_block ? VM_ALLOW_HUGE_VMAP:0,
 			node, __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__kvmalloc_node_noprof);
_

Patches currently in -mm which might be from urezki@gmail.com are