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[PATCH] riscv: patch: Avoid early page_to_phys()

Vivian Wang posted 1 patch 4 weeks, 1 day ago 
arch/riscv/kernel/patch.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
[PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Vivian Wang 4 weeks, 1 day ago 
Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
page_to_phys()"), avoid using phys_to_page() for the kernel address case
in patch_map().

Since this is called from apply_boot_alternatives() in setup_arch(), and
commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
memory model") has moved sparse_init() to after setup_arch(),
phys_to_page() is not available there yet, and it panics on boot with
SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.

Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
---
checkpatch.pl complains about the BUG_ON which was already there
---
 arch/riscv/kernel/patch.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index db13c9ddf9e3..16b243376f36 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -42,19 +42,20 @@ static inline bool is_kernel_exittext(uintptr_t addr)
 static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
 {
 	uintptr_t uintaddr = (uintptr_t) addr;
-	struct page *page;
+	phys_addr_t phys;
 
-	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))
-		page = phys_to_page(__pa_symbol(addr));
-	else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
-		page = vmalloc_to_page(addr);
-	else
+	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) {
+		phys = __pa_symbol(addr);
+	} else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
+		struct page *page = vmalloc_to_page(addr);
+
+		BUG_ON(!page);
+		phys = page_to_phys(page) + offset_in_page(addr);
+	} else {
 		return addr;
+	}
 
-	BUG_ON(!page);
-
-	return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
-					 offset_in_page(addr));
+	return (void *)set_fixmap_offset(fixmap, phys);
 }
 
 static void patch_unmap(int fixmap)

---
base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
change-id: 20260310-riscv-sparsemem-alternatives-fix-f9ea051b1694

Best regards,
-- 
Vivian "dramforever" Wang
Re: [PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Paul Walmsley 3 weeks ago 
On Tue, 10 Mar 2026, Vivian Wang wrote:

> Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
> page_to_phys()"), avoid using phys_to_page() for the kernel address case
> in patch_map().
> 
> Since this is called from apply_boot_alternatives() in setup_arch(), and
> commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
> memory model") has moved sparse_init() to after setup_arch(),
> phys_to_page() is not available there yet, and it panics on boot with
> SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.
> 
> Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
> Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
> Suggested-by: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>

Thanks, queued for v7.0-rc.


- Paul
Re: [PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Vivian Wang 2 weeks, 3 days ago 
Hi Andrew and Paul,

On 3/19/26 01:42, Paul Walmsley wrote:
> On Tue, 10 Mar 2026, Vivian Wang wrote:
>
>> Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
>> page_to_phys()"), avoid using phys_to_page() for the kernel address case
>> in patch_map().
>>
>> Since this is called from apply_boot_alternatives() in setup_arch(), and
>> commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
>> memory model") has moved sparse_init() to after setup_arch(),
>> phys_to_page() is not available there yet, and it panics on boot with
>> SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.
>>
>> Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
>> Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
>> Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
>> Suggested-by: Mike Rapoport <rppt@kernel.org>
>> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
> Thanks, queued for v7.0-rc.

I have only just noticed that this patch was commited to both
mm-hotfixes-stable [1] by Andrew and riscv fixes [2] by Paul. Is this
intended?

While we're at it, Paul's subject correction is correct - it should have
said phys_to_page(), not page_to_phys(). Not that I can blame this on
anyone else, but apparently I wrote it while looking at the arm64 commit
without noticing.

Thanks and sorry for the hopefully minor inconvenience.

Vivian "dramforever" Wang

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?h=mm-hotfixes-stable&id=ac5f2c1256ede8b0acb2661f6441530d53d8f126
[2]: https://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git/commit/?h=fixes&id=3a876501fd9aaae9845026f046379c9507365bb5
Re: [PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Andrew Morton 2 weeks, 2 days ago 
On Mon, 23 Mar 2026 09:58:05 +0800 Vivian Wang <wangruikang@iscas.ac.cn> wrote:

> On 3/19/26 01:42, Paul Walmsley wrote:
> > On Tue, 10 Mar 2026, Vivian Wang wrote:
> >
> >> Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
> >> page_to_phys()"), avoid using phys_to_page() for the kernel address case
> >> in patch_map().
> >>
> >> Since this is called from apply_boot_alternatives() in setup_arch(), and
> >> commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
> >> memory model") has moved sparse_init() to after setup_arch(),
> >> phys_to_page() is not available there yet, and it panics on boot with
> >> SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.
> >>
> >> Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> >> Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
> >> Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
> >> Suggested-by: Mike Rapoport <rppt@kernel.org>
> >> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
> > Thanks, queued for v7.0-rc.
> 
> I have only just noticed that this patch was commited to both
> mm-hotfixes-stable [1] by Andrew and riscv fixes [2] by Paul. Is this
> intended?

It happens - better both than neither!

I'll drop the mm.git copy.
Re: [PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Mike Rapoport 4 weeks, 1 day ago 
On Tue, Mar 10, 2026 at 04:25:33PM +0800, Vivian Wang wrote:
> Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
> page_to_phys()"), avoid using phys_to_page() for the kernel address case
> in patch_map().
> 
> Since this is called from apply_boot_alternatives() in setup_arch(), and
> commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
> memory model") has moved sparse_init() to after setup_arch(),
> phys_to_page() is not available there yet, and it panics on boot with
> SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.
> 
> Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
> Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
> Suggested-by: Mike Rapoport <rppt@kernel.org>

Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
> ---
> checkpatch.pl complains about the BUG_ON which was already there
> ---
>  arch/riscv/kernel/patch.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
> index db13c9ddf9e3..16b243376f36 100644
> --- a/arch/riscv/kernel/patch.c
> +++ b/arch/riscv/kernel/patch.c
> @@ -42,19 +42,20 @@ static inline bool is_kernel_exittext(uintptr_t addr)
>  static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
>  {
>  	uintptr_t uintaddr = (uintptr_t) addr;
> -	struct page *page;
> +	phys_addr_t phys;
>  
> -	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr))
> -		page = phys_to_page(__pa_symbol(addr));
> -	else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
> -		page = vmalloc_to_page(addr);
> -	else
> +	if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) {
> +		phys = __pa_symbol(addr);
> +	} else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
> +		struct page *page = vmalloc_to_page(addr);
> +
> +		BUG_ON(!page);
> +		phys = page_to_phys(page) + offset_in_page(addr);
> +	} else {
>  		return addr;
> +	}
>  
> -	BUG_ON(!page);
> -
> -	return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
> -					 offset_in_page(addr));
> +	return (void *)set_fixmap_offset(fixmap, phys);
>  }
>  
>  static void patch_unmap(int fixmap)
> 
> ---
> base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681
> change-id: 20260310-riscv-sparsemem-alternatives-fix-f9ea051b1694
> 
> Best regards,
> -- 
> Vivian "dramforever" Wang
> 

-- 
Sincerely yours,
Mike.
Re: [PATCH] riscv: patch: Avoid early page_to_phys()
Posted by Thomas Weißschuh 4 weeks, 1 day ago 
On Tue, Mar 10, 2026 at 04:25:33PM +0800, Vivian Wang wrote:
> Similarly to commit 8d09e2d569f6 ("arm64: patching: avoid early
> page_to_phys()"), avoid using phys_to_page() for the kernel address case
> in patch_map().
> 
> Since this is called from apply_boot_alternatives() in setup_arch(), and
> commit 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE
> memory model") has moved sparse_init() to after setup_arch(),
> phys_to_page() is not available there yet, and it panics on boot with
> SPARSEMEM on RV32, which does not use SPARSEMEM_VMEMMAP.
> 
> Reported-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> Closes: https://lore.kernel.org/r/20260223144108-dcace0b9-02e8-4b67-a7ce-f263bed36f26@linutronix.de/
> Fixes: 4267739cabb8 ("arch, mm: consolidate initialization of SPARSE memory model")
> Suggested-by: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>

Thanks!

Tested-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

(...)

Thomas

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