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From: Christian Brauner <brauner@kernel.org>
To: linux-fsdevel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	 Breno Leitao <leitao@debian.org>, Chris Mason <mason@kernel.org>,
	 Thomas Gleixner <tglx@kernel.org>,
	x86@kernel.org,  kexec@lists.infradead.org,
	linuxppc-dev@lists.ozlabs.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org,  loongarch@lists.linux.dev,
	linux-mips@vger.kernel.org,  linux-sh@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	 David Hildenbrand <david@kernel.org>,
	 "Christian Brauner (Amutable)" <brauner@kernel.org>
Subject: [PATCH RFC 4/4] crash_dump: use copy_oldmem_to_iter() everywhere
Date: Thu, 12 Nov 2026 17:37:10 +0100	[thread overview]
Message-ID: <20261112-work-procfs-oldmem-v1-4-ecdcafd99265@kernel.org> (raw)
In-Reply-To: <20261112-work-procfs-oldmem-v1-0-ecdcafd99265@kernel.org>

Make the remaining copy_oldmem_page() implementations copy the page of
the crashed kernel with copy_oldmem_to_iter() like x86_64 and powerpc
do. None of these architectures has a machine check safe copy today, so
for them this is copy_to_iter() under another name. But the copy of a
page of the old kernel is in one place now, and an architecture that
gains ARCH_HAS_COPY_MC later gets the recovery without touching its
crash dump code.

s390 stays as it is. It copies the old kernel's memory through its real
address mode window in memcpy_real_iter(), and an uncorrected storage
error is fatal on s390 anyway (cf. s390_handle_damage()).

No functional changes.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 arch/arm/kernel/crash_dump.c       | 2 +-
 arch/arm64/kernel/crash_dump.c     | 2 +-
 arch/loongarch/kernel/crash_dump.c | 2 +-
 arch/mips/kernel/crash_dump.c      | 2 +-
 arch/riscv/kernel/crash_dump.c     | 2 +-
 arch/sh/kernel/crash_dump.c        | 2 +-
 arch/x86/kernel/crash_dump_32.c    | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kernel/crash_dump.c b/arch/arm/kernel/crash_dump.c
index 938bd932df9a0..0f2628872b00c 100644
--- a/arch/arm/kernel/crash_dump.c
+++ b/arch/arm/kernel/crash_dump.c
@@ -28,7 +28,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	iounmap(vaddr);
 	return csize;
diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c
index 670e4ce818223..c774b3aba107d 100644
--- a/arch/arm64/kernel/crash_dump.c
+++ b/arch/arm64/kernel/crash_dump.c
@@ -24,7 +24,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 
diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c
index e559307c10929..03a136b8be8da 100644
--- a/arch/loongarch/kernel/crash_dump.c
+++ b/arch/loongarch/kernel/crash_dump.c
@@ -15,7 +15,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 
diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
index 6e50f49024094..078c0d1e8df46 100644
--- a/arch/mips/kernel/crash_dump.c
+++ b/arch/mips/kernel/crash_dump.c
@@ -12,7 +12,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 		return 0;
 
 	vaddr = kmap_local_pfn(pfn);
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	kunmap_local(vaddr);
 
 	return csize;
diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c
index ea2158cee97b3..0820e3db12603 100644
--- a/arch/riscv/kernel/crash_dump.c
+++ b/arch/riscv/kernel/crash_dump.c
@@ -21,7 +21,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 	return csize;
diff --git a/arch/sh/kernel/crash_dump.c b/arch/sh/kernel/crash_dump.c
index 85c0e58f1a59f..2a5988b6e9d7a 100644
--- a/arch/sh/kernel/crash_dump.c
+++ b/arch/sh/kernel/crash_dump.c
@@ -23,7 +23,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	iounmap(vaddr);
 
 	return csize;
diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index 5f4ae5476e193..cb202d4e1f703 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c
@@ -40,7 +40,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
 		return -EFAULT;
 
 	vaddr = kmap_local_pfn(pfn);
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	kunmap_local(vaddr);
 
 	return csize;

-- 
2.53.0


WARNING: multiple messages have this Message-ID (diff)
From: Christian Brauner <brauner@kernel.org>
To: linux-fsdevel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	 Breno Leitao <leitao@debian.org>, Chris Mason <mason@kernel.org>,
	 Thomas Gleixner <tglx@kernel.org>,
	x86@kernel.org,  kexec@lists.infradead.org,
	linuxppc-dev@lists.ozlabs.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org,  loongarch@lists.linux.dev,
	linux-mips@vger.kernel.org,  linux-sh@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	 David Hildenbrand <david@kernel.org>,
	 "Christian Brauner (Amutable)" <brauner@kernel.org>
Subject: [PATCH RFC 4/4] crash_dump: use copy_oldmem_to_iter() everywhere
Date: Thu, 12 Nov 2026 17:37:10 +0100	[thread overview]
Message-ID: <20261112-work-procfs-oldmem-v1-4-ecdcafd99265@kernel.org> (raw)
In-Reply-To: <20261112-work-procfs-oldmem-v1-0-ecdcafd99265@kernel.org>

Make the remaining copy_oldmem_page() implementations copy the page of
the crashed kernel with copy_oldmem_to_iter() like x86_64 and powerpc
do. None of these architectures has a machine check safe copy today, so
for them this is copy_to_iter() under another name. But the copy of a
page of the old kernel is in one place now, and an architecture that
gains ARCH_HAS_COPY_MC later gets the recovery without touching its
crash dump code.

s390 stays as it is. It copies the old kernel's memory through its real
address mode window in memcpy_real_iter(), and an uncorrected storage
error is fatal on s390 anyway (cf. s390_handle_damage()).

No functional changes.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 arch/arm/kernel/crash_dump.c       | 2 +-
 arch/arm64/kernel/crash_dump.c     | 2 +-
 arch/loongarch/kernel/crash_dump.c | 2 +-
 arch/mips/kernel/crash_dump.c      | 2 +-
 arch/riscv/kernel/crash_dump.c     | 2 +-
 arch/sh/kernel/crash_dump.c        | 2 +-
 arch/x86/kernel/crash_dump_32.c    | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kernel/crash_dump.c b/arch/arm/kernel/crash_dump.c
index 938bd932df9a0..0f2628872b00c 100644
--- a/arch/arm/kernel/crash_dump.c
+++ b/arch/arm/kernel/crash_dump.c
@@ -28,7 +28,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	iounmap(vaddr);
 	return csize;
diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c
index 670e4ce818223..c774b3aba107d 100644
--- a/arch/arm64/kernel/crash_dump.c
+++ b/arch/arm64/kernel/crash_dump.c
@@ -24,7 +24,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 
diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c
index e559307c10929..03a136b8be8da 100644
--- a/arch/loongarch/kernel/crash_dump.c
+++ b/arch/loongarch/kernel/crash_dump.c
@@ -15,7 +15,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 
diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
index 6e50f49024094..078c0d1e8df46 100644
--- a/arch/mips/kernel/crash_dump.c
+++ b/arch/mips/kernel/crash_dump.c
@@ -12,7 +12,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 		return 0;
 
 	vaddr = kmap_local_pfn(pfn);
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	kunmap_local(vaddr);
 
 	return csize;
diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c
index ea2158cee97b3..0820e3db12603 100644
--- a/arch/riscv/kernel/crash_dump.c
+++ b/arch/riscv/kernel/crash_dump.c
@@ -21,7 +21,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 
 	memunmap(vaddr);
 	return csize;
diff --git a/arch/sh/kernel/crash_dump.c b/arch/sh/kernel/crash_dump.c
index 85c0e58f1a59f..2a5988b6e9d7a 100644
--- a/arch/sh/kernel/crash_dump.c
+++ b/arch/sh/kernel/crash_dump.c
@@ -23,7 +23,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
 	if (!vaddr)
 		return -ENOMEM;
 
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	iounmap(vaddr);
 
 	return csize;
diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index 5f4ae5476e193..cb202d4e1f703 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c
@@ -40,7 +40,7 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
 		return -EFAULT;
 
 	vaddr = kmap_local_pfn(pfn);
-	csize = copy_to_iter(vaddr + offset, csize, iter);
+	csize = copy_oldmem_to_iter(vaddr + offset, csize, iter);
 	kunmap_local(vaddr);
 
 	return csize;

-- 
2.53.0


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2026-11-12 16:38 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-12 16:37 [PATCH RFC 0/4] crash_dump: recover from machine checks in copy_oldmem_page() Christian Brauner
2026-11-12 16:37 ` Christian Brauner
2026-11-12 16:37 ` [PATCH RFC 1/4] powerpc/crash_dump: check ioremap_cache() " Christian Brauner
2026-11-12 16:37   ` Christian Brauner
2026-11-12 16:45   ` sashiko-bot
2026-11-12 19:10   ` Geert Uytterhoeven
2026-11-12 19:10     ` Geert Uytterhoeven
2026-11-12 16:37 ` [PATCH RFC 2/4] sh/crash_dump: check ioremap() " Christian Brauner
2026-11-12 16:37   ` Christian Brauner
2026-11-12 16:42   ` sashiko-bot
2026-11-12 19:07   ` Geert Uytterhoeven
2026-11-12 19:07     ` Geert Uytterhoeven
2026-11-12 16:37 ` [PATCH RFC 3/4] crash_dump: recover from a machine check " Christian Brauner
2026-11-12 16:37   ` Christian Brauner
2026-11-12 16:50   ` sashiko-bot
2026-11-12 16:37 ` Christian Brauner [this message]
2026-11-12 16:37   ` [PATCH RFC 4/4] crash_dump: use copy_oldmem_to_iter() everywhere Christian Brauner
2026-11-12 16:43   ` sashiko-bot
2026-11-12 16:40 ` [PATCH RFC 0/4] crash_dump: recover from machine checks in copy_oldmem_page() Christian Brauner
2026-11-12 16:40   ` Christian Brauner

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