FAILED: patch "[PATCH] raid6: add missing vzeroupper to AVX-512 code" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] raid6: add missing vzeroupper to AVX-512 code" failed to apply to 6.18-stable tree

[Sasha Levin]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x b82cf9e49c1be7cf1fd8e1bd806b0cdd25ab8127
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107050912-failed-6.18-b82cf9e49c1b@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From b82cf9e49c1be7cf1fd8e1bd806b0cdd25ab8127 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@kernel.org>
Date: Mon, 31 Aug 2026 14:23:16 -0700
Subject: [PATCH] raid6: add missing vzeroupper to AVX-512 code

Since the AVX-512 optimized RAID6 code uses ZMM registers, execute
vzeroupper before returning from it.  This is needed to avoid degrading
the performance of any later SSE code that may happen to be executed.

Link: https://lore.kernel.org/20260831212316.213896-1-ebiggers@kernel.org
Fixes: e0a491c12968 ("lib/raid6: Add AVX512 optimized gen_syndrome functions")
Fixes: 13c520b2993c ("lib/raid6: Add AVX512 optimized recovery functions")
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
---
 lib/raid/raid6/x86/avx512.c       | 6 ++++++
 lib/raid/raid6/x86/recov_avx512.c | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/lib/raid/raid6/x86/avx512.c b/lib/raid/raid6/x86/avx512.c
index e671eb5bde63e..772bfc4af6dfd 100644
--- a/lib/raid/raid6/x86/avx512.c
+++ b/lib/raid/raid6/x86/avx512.c
@@ -78,6 +78,7 @@ static void raid6_avx5121_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -137,6 +138,7 @@ static void raid6_avx5121_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -208,6 +210,7 @@ static void raid6_avx5122_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -292,6 +295,7 @@ static void raid6_avx5122_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -396,6 +400,7 @@ static void raid6_avx5124_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -529,6 +534,7 @@ static void raid6_avx5124_xor_syndrome(int disks, int start, int stop,
 			       "m" (q[d+128]), "m" (q[d+192]));
 	}
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 const struct raid6_calls raid6_avx512x4 = {
diff --git a/lib/raid/raid6/x86/recov_avx512.c b/lib/raid/raid6/x86/recov_avx512.c
index ec72d5a30c01e..299a3f044d616 100644
--- a/lib/raid/raid6/x86/recov_avx512.c
+++ b/lib/raid/raid6/x86/recov_avx512.c
@@ -211,6 +211,7 @@ static void raid6_2data_recov_avx512(int disks, size_t bytes, int faila,
 #endif
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -353,6 +354,7 @@ static void raid6_datap_recov_avx512(int disks, size_t bytes, int faila,
 #endif
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
-- 
2.53.0

Re: FAILED: patch "[PATCH] raid6: add missing vzeroupper to AVX-512 code" failed to apply to 6.18-stable tree

[Eric Biggers]

On Sat, Nov 07, 2026 at 05:09:12AM -0500, Sasha Levin wrote:
> The patch below does not apply to the 6.18-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
> git checkout FETCH_HEAD
> git cherry-pick -x b82cf9e49c1be7cf1fd8e1bd806b0cdd25ab8127
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107050912-failed-6.18-b82cf9e49c1b@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'
> 
> Thanks,
> Sasha

Actually a clean cherry-pick, and failed to Cc the raid mailing list.

- Eric