FAILED: patch "[PATCH] riscv: use an atomic xchg in pudp_huge_get_and_clear()" failed to apply to 6.17-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.17-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-6.17.y
git checkout FETCH_HEAD
git cherry-pick -x 668208b161a0b679427e7d0f34c0a65fd7d23979
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101914-dodge-paprika-36e0@gregkh' --subject-prefix 'PATCH 6.17.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 668208b161a0b679427e7d0f34c0a65fd7d23979 Mon Sep 17 00:00:00 2001
From: Alexandre Ghiti <alexghiti@rivosinc.com>
Date: Thu, 14 Aug 2025 12:06:14 +0000
Subject: [PATCH] riscv: use an atomic xchg in pudp_huge_get_and_clear()

Make sure we return the right pud value and not a value that could have
been overwritten in between by a different core.

Link: https://lkml.kernel.org/r/20250814-dev-alex-thp_pud_xchg-v1-1-b4704dfae206@rivosinc.com
Fixes: c3cc2a4a3a23 ("riscv: Add support for PUD THP")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrew Donnellan <ajd@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 91697fbf1f90..e69346307e78 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -942,6 +942,17 @@ static inline int pudp_test_and_clear_young(struct vm_area_struct *vma,
 	return ptep_test_and_clear_young(vma, address, (pte_t *)pudp);
 }
 
+#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR
+static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
+					    unsigned long address, pud_t *pudp)
+{
+	pud_t pud = __pud(atomic_long_xchg((atomic_long_t *)pudp, 0));
+
+	page_table_check_pud_clear(mm, pud);
+
+	return pud;
+}
+
 static inline int pud_young(pud_t pud)
 {
 	return pte_young(pud_pte(pud));