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[PATCH] mm/vmalloc: Do not warn on -ENOMEM from va_alloc()

Uladzislau Rezki (Sony) posted 1 patch 2 months ago 
mm/vmalloc.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
[PATCH] mm/vmalloc: Do not warn on -ENOMEM from va_alloc()
Posted by Uladzislau Rezki (Sony) 2 months ago 
Since vmalloc() accepts non-blocking GFP flags, allocation
requests may fail when callers pass restrictive GFP masks.

va_clip() may return -ENOMEM when its GFP_NOWAIT fallback
allocation fails during NE_FIT_TYPE splitting. This is an
expected failure, so va_alloc() should return the error
without triggering a kernel splat.

Reported-by: syzbot+61c997e6be1d9bb300ba@syzkaller.appspotmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 mm/vmalloc.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 1afca3568b9b..7a0cbba3d29d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1817,8 +1817,10 @@ va_alloc(struct vmap_area *va,
 
 	/* Update the free vmap_area. */
 	ret = va_clip(root, head, va, nva_start_addr, size);
-	if (WARN_ON_ONCE(ret))
+	if (ret) {
+		WARN_ON_ONCE(ret != -ENOMEM);
 		return ret;
+	}
 
 	return nva_start_addr;
 }
@@ -1891,12 +1893,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node)
 
 	/*
 	 * Preload this CPU with one extra vmap_area object. It is used
-	 * when fit type of free area is NE_FIT_TYPE. It guarantees that
-	 * a CPU that does an allocation is preloaded.
-	 *
-	 * We do it in non-atomic context, thus it allows us to use more
-	 * permissive allocation masks to be more stable under low memory
-	 * condition and high memory pressure.
+	 * when fit type of free area is NE_FIT_TYPE. It is best effort
+	 * pre-loading. If it fails va_clip() may return -ENOMEM from its
+	 * GFP_NOWAIT fallback.
 	 */
 	if (!this_cpu_read(ne_fit_preload_node))
 		va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
-- 
2.47.3
Re: [PATCH] mm/vmalloc: Do not warn on -ENOMEM from va_alloc()
Posted by Baoquan He 2 months ago 
On 08/02/26 at 12:46pm, Uladzislau Rezki (Sony) wrote:
> Since vmalloc() accepts non-blocking GFP flags, allocation
> requests may fail when callers pass restrictive GFP masks.
> 
> va_clip() may return -ENOMEM when its GFP_NOWAIT fallback
> allocation fails during NE_FIT_TYPE splitting. This is an
> expected failure, so va_alloc() should return the error
> without triggering a kernel splat.
> 
> Reported-by: syzbot+61c997e6be1d9bb300ba@syzkaller.appspotmail.com
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
>  mm/vmalloc.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1afca3568b9b..7a0cbba3d29d 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1817,8 +1817,10 @@ va_alloc(struct vmap_area *va,
>  
>  	/* Update the free vmap_area. */
>  	ret = va_clip(root, head, va, nva_start_addr, size);
> -	if (WARN_ON_ONCE(ret))
> +	if (ret) {
> +		WARN_ON_ONCE(ret != -ENOMEM);
>  		return ret;
> +	}
>  
>  	return nva_start_addr;
>  }
> @@ -1891,12 +1893,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node)
>  
>  	/*
>  	 * Preload this CPU with one extra vmap_area object. It is used
> -	 * when fit type of free area is NE_FIT_TYPE. It guarantees that
> -	 * a CPU that does an allocation is preloaded.
> -	 *
> -	 * We do it in non-atomic context, thus it allows us to use more
> -	 * permissive allocation masks to be more stable under low memory
> -	 * condition and high memory pressure.
> +	 * when fit type of free area is NE_FIT_TYPE. It is best effort
> +	 * pre-loading. If it fails va_clip() may return -ENOMEM from its
> +	 * GFP_NOWAIT fallback.
>  	 */
>  	if (!this_cpu_read(ne_fit_preload_node))
>  		va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);

LGTM,

Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Re: [PATCH] mm/vmalloc: Do not warn on -ENOMEM from va_alloc()
Posted by Anshuman Khandual 2 months ago 
On Sun, Aug 02, 2026 at 12:46:27PM +0200, Uladzislau Rezki (Sony) wrote:
> Since vmalloc() accepts non-blocking GFP flags, allocation
> requests may fail when callers pass restrictive GFP masks.
> 
> va_clip() may return -ENOMEM when its GFP_NOWAIT fallback
> allocation fails during NE_FIT_TYPE splitting. This is an
> expected failure, so va_alloc() should return the error
> without triggering a kernel splat.

Dropping WARN_ON_ONCE() just for -ENOMEM while preserving this
warning for other returned errors does make sense.

> 
> Reported-by: syzbot+61c997e6be1d9bb300ba@syzkaller.appspotmail.com

Very small nit.

If there is actual link for the problem report, probably it could
be added as an Link: or Closes: here.


> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  mm/vmalloc.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1afca3568b9b..7a0cbba3d29d 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1817,8 +1817,10 @@ va_alloc(struct vmap_area *va,
>  
>  	/* Update the free vmap_area. */
>  	ret = va_clip(root, head, va, nva_start_addr, size);
> -	if (WARN_ON_ONCE(ret))
> +	if (ret) {
> +		WARN_ON_ONCE(ret != -ENOMEM);
>  		return ret;
> +	}
>  
>  	return nva_start_addr;
>  }
> @@ -1891,12 +1893,9 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node)
>  
>  	/*
>  	 * Preload this CPU with one extra vmap_area object. It is used
> -	 * when fit type of free area is NE_FIT_TYPE. It guarantees that
> -	 * a CPU that does an allocation is preloaded.
> -	 *
> -	 * We do it in non-atomic context, thus it allows us to use more
> -	 * permissive allocation masks to be more stable under low memory
> -	 * condition and high memory pressure.
> +	 * when fit type of free area is NE_FIT_TYPE. It is best effort
> +	 * pre-loading. If it fails va_clip() may return -ENOMEM from its
> +	 * GFP_NOWAIT fallback.
>  	 */
>  	if (!this_cpu_read(ne_fit_preload_node))
>  		va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
> -- 
> 2.47.3
>
Re: [PATCH] mm/vmalloc: Do not warn on -ENOMEM from va_alloc()
Posted by Uladzislau Rezki 1 month, 4 weeks ago 
On Mon, Aug 03, 2026 at 09:19:52AM +0530, Anshuman Khandual wrote:
> On Sun, Aug 02, 2026 at 12:46:27PM +0200, Uladzislau Rezki (Sony) wrote:
> > Since vmalloc() accepts non-blocking GFP flags, allocation
> > requests may fail when callers pass restrictive GFP masks.
> > 
> > va_clip() may return -ENOMEM when its GFP_NOWAIT fallback
> > allocation fails during NE_FIT_TYPE splitting. This is an
> > expected failure, so va_alloc() should return the error
> > without triggering a kernel splat.
> 
> Dropping WARN_ON_ONCE() just for -ENOMEM while preserving this
> warning for other returned errors does make sense.
> 
> > 
> > Reported-by: syzbot+61c997e6be1d9bb300ba@syzkaller.appspotmail.com
> 
> Very small nit.
> 
> If there is actual link for the problem report, probably it could
> be added as an Link: or Closes: here.
> 
I hope Andrew can help here. If not i will resend!

Thank you!

--
Uladzislau Rezki

Patchew 2.1-devel-ea86937

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