+ mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area.patch added to mm-new branch

+ mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/vmalloc.c: return explicit error value in alloc_vmap_area()
has been added to the -mm mm-new branch.  Its filename is
     mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Baoquan He <bhe@redhat.com>
Subject: mm/vmalloc.c: return explicit error value in alloc_vmap_area()
Date: Sat, 19 Apr 2025 06:36:53 +0800

In codes of alloc_vmap_area(), it returns the upper bound 'vend' to
indicate if the allocation is successful or failed.  That is not very
clear.

Here change to return explicit error values and check them to judge if
allocation is successful.

Link: https://lkml.kernel.org/r/20250418223653.243436-6-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Shivank Garg <shivankg@amd.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmalloc.c |   27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

--- a/mm/vmalloc.c~mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area
+++ a/mm/vmalloc.c
@@ -1716,7 +1716,7 @@ va_clip(struct rb_root *root, struct lis
 			 */
 			lva = kmem_cache_alloc(vmap_area_cachep, GFP_NOWAIT);
 			if (!lva)
-				return -1;
+				return -ENOMEM;
 		}
 
 		/*
@@ -1730,7 +1730,7 @@ va_clip(struct rb_root *root, struct lis
 		 */
 		va->va_start = nva_start_addr + size;
 	} else {
-		return -1;
+		return -EINVAL;
 	}
 
 	if (type != FL_FIT_TYPE) {
@@ -1759,19 +1759,19 @@ va_alloc(struct vmap_area *va,
 
 	/* Check the "vend" restriction. */
 	if (nva_start_addr + size > vend)
-		return vend;
+		return -ERANGE;
 
 	/* Update the free vmap_area. */
 	ret = va_clip(root, head, va, nva_start_addr, size);
 	if (WARN_ON_ONCE(ret))
-		return vend;
+		return ret;
 
 	return nva_start_addr;
 }
 
 /*
  * Returns a start address of the newly allocated area, if success.
- * Otherwise a vend is returned that indicates failure.
+ * Otherwise an error value is returned that indicates failure.
  */
 static __always_inline unsigned long
 __alloc_vmap_area(struct rb_root *root, struct list_head *head,
@@ -1796,14 +1796,13 @@ __alloc_vmap_area(struct rb_root *root,
 
 	va = find_vmap_lowest_match(root, size, align, vstart, adjust_search_size);
 	if (unlikely(!va))
-		return vend;
+		return -ENOENT;
 
 	nva_start_addr = va_alloc(va, root, head, size, align, vstart, vend);
-	if (nva_start_addr == vend)
-		return vend;
 
 #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
-	find_vmap_lowest_match_check(root, head, size, align);
+	if (!IS_ERR_VALUE(nva_start_addr))
+		find_vmap_lowest_match_check(root, head, size, align);
 #endif
 
 	return nva_start_addr;
@@ -1933,7 +1932,7 @@ node_alloc(unsigned long size, unsigned
 	struct vmap_area *va;
 
 	*vn_id = 0;
-	*addr = vend;
+	*addr = -EINVAL;
 
 	/*
 	 * Fallback to a global heap if not vmalloc or there
@@ -2013,20 +2012,20 @@ static struct vmap_area *alloc_vmap_area
 	}
 
 retry:
-	if (addr == vend) {
+	if (IS_ERR_VALUE(addr)) {
 		preload_this_cpu_lock(&free_vmap_area_lock, gfp_mask, node);
 		addr = __alloc_vmap_area(&free_vmap_area_root, &free_vmap_area_list,
 			size, align, vstart, vend);
 		spin_unlock(&free_vmap_area_lock);
 	}
 
-	trace_alloc_vmap_area(addr, size, align, vstart, vend, addr == vend);
+	trace_alloc_vmap_area(addr, size, align, vstart, vend, IS_ERR_VALUE(addr));
 
 	/*
-	 * If an allocation fails, the "vend" address is
+	 * If an allocation fails, the error value is
 	 * returned. Therefore trigger the overflow path.
 	 */
-	if (unlikely(addr == vend))
+	if (IS_ERR_VALUE(addr))
 		goto overflow;
 
 	va->va_start = addr;
_

Patches currently in -mm which might be from bhe@redhat.com are

mm-gup-remove-unneeded-checking-in-follow_page_pte.patch
mm-gup-remove-gup_fast_pgd_leaf-and-clean-up-the-relevant-codes.patch
mm-gup-clean-up-codes-in-fault_in_xxx-functions.patch
mm-gup-clean-up-codes-in-fault_in_xxx-functions-v5.patch
mm-vmallocc-change-purge_ndoes-as-local-static-variable.patch
mm-vmallocc-find-the-vmap-of-vmap_nodes-in-reverse-order.patch
mm-vmallocc-optimize-code-in-decay_va_pool_node-a-little-bit.patch
mm-vmalloc-optimize-function-vm_unmap_aliases.patch
mm-vmallocc-return-explicit-error-value-in-alloc_vmap_area.patch