FAILED: patch "[PATCH] raid6: add missing vzeroupper to AVX2 code" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] raid6: add missing vzeroupper to AVX2 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 24f1241cdb056fd630e6710a916e0f7c8c910a70
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107050910-failed-6.18-24f1241cdb05@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Thanks,
Sasha

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

From 24f1241cdb056fd630e6710a916e0f7c8c910a70 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@kernel.org>
Date: Mon, 31 Aug 2026 14:23:08 -0700
Subject: [PATCH] raid6: add missing vzeroupper to AVX2 code

Since the AVX2 optimized RAID6 code uses YMM 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/20260831212308.213855-1-ebiggers@kernel.org
Fixes: 2c935842bdb4 ("lib/raid6: Add AVX2 optimized gen_syndrome functions")
Fixes: 7056741fd9fc ("lib/raid6: Add AVX2 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/avx2.c       | 6 ++++++
 lib/raid/raid6/x86/recov_avx2.c | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/lib/raid/raid6/x86/avx2.c b/lib/raid/raid6/x86/avx2.c
index 7d829c669ea79..3cc2fe7ac42c5 100644
--- a/lib/raid/raid6/x86/avx2.c
+++ b/lib/raid/raid6/x86/avx2.c
@@ -67,6 +67,7 @@ static void raid6_avx21_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -115,6 +116,7 @@ static void raid6_avx21_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -175,6 +177,7 @@ static void raid6_avx22_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -243,6 +246,7 @@ static void raid6_avx22_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -334,6 +338,7 @@ static void raid6_avx24_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -444,6 +449,7 @@ static void raid6_avx24_xor_syndrome(int disks, int start, int stop,
 		asm volatile("vmovntdq %%ymm14,%0" : "=m" (q[d+96]));
 	}
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
diff --git a/lib/raid/raid6/x86/recov_avx2.c b/lib/raid/raid6/x86/recov_avx2.c
index a714a780a2d8f..820871046e305 100644
--- a/lib/raid/raid6/x86/recov_avx2.c
+++ b/lib/raid/raid6/x86/recov_avx2.c
@@ -176,6 +176,7 @@ static void raid6_2data_recov_avx2(int disks, size_t bytes, int faila,
 #endif
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -293,6 +294,7 @@ static void raid6_datap_recov_avx2(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 AVX2 code" failed to apply to 6.18-stable tree

[Eric Biggers]

On Sat, Nov 07, 2026 at 05:09:10AM -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 24f1241cdb056fd630e6710a916e0f7c8c910a70
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107050910-failed-6.18-24f1241cdb05@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