If ARCH_HAS_FLUSH_ON_KUNMAP is defined (PA-RISC case), __kunmap_local()
calls kunmap_flush_on_unmap(). The latter currently flushes the wrong
address (as confirmed by Matthew Wilcox and Helge Deller). Al Viro
proposed to call kunmap_flush_on_unmap() on an aligned-down to page
address in order to fix this issue. Consensus has been reached on this
solution.
Therefore, if ARCH_HAS_FLUSH_ON_KUNMAP is defined, call
kunmap_flush_on_unmap() on an aligned-down to page address computed with
the PTR_ALIGN_DOWN() macro.
Cc: Ira Weiny <[email protected]>
Suggested-by: Al Viro <[email protected]>
Confirmed-by: Helge Deller <[email protected]>
Confirmed-by: Matthew Wilcox <[email protected]>
Fixes: f3ba3c710ac5 ("mm/highmem: Provide kmap_local*")
Signed-off-by: Fabio M. De Francesco <[email protected]>
---
I have (at least) two problems with this patch...
1) checkpatch.pl complains about the use of the non-standard
"Confirmed-by" tags. I don't know how else I can give credit to Helge
and Matthew. However, this is not the first time that I see non-standard
tags in patches applied upstream (I too had a non-standard
"Analysed-by" tag in patch which fixes a SAC bug). Any objections?
2) I'm not sure whether or not the "Fixes" tag is appropriate in this
patch. Can someone either confirm or deny it?
include/linux/highmem-internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index 034b1106d022..e247c9ac4583 100644
--- a/include/linux/highmem-internal.h
+++ b/include/linux/highmem-internal.h
@@ -200,7 +200,7 @@ static inline void *kmap_local_pfn(unsigned long pfn)
static inline void __kunmap_local(const void *addr)
{
#ifdef ARCH_HAS_FLUSH_ON_KUNMAP
- kunmap_flush_on_unmap(addr);
+ kunmap_flush_on_unmap(PTR_ALIGN_DOWN(addr, PAGE_SIZE));
#endif
}
--
2.39.0
On gioved? 26 gennaio 2023 15:11:44 CET Fabio M. De Francesco wrote:
> If ARCH_HAS_FLUSH_ON_KUNMAP is defined (PA-RISC case), __kunmap_local()
> calls kunmap_flush_on_unmap(). The latter currently flushes the wrong
> address (as confirmed by Matthew Wilcox and Helge Deller). Al Viro
> proposed to call kunmap_flush_on_unmap() on an aligned-down to page
> address in order to fix this issue. Consensus has been reached on this
> solution.
>
> Therefore, if ARCH_HAS_FLUSH_ON_KUNMAP is defined, call
> kunmap_flush_on_unmap() on an aligned-down to page address computed with
> the PTR_ALIGN_DOWN() macro.
>
> Cc: Ira Weiny <[email protected]>
> Suggested-by: Al Viro <[email protected]>
> Confirmed-by: Helge Deller <[email protected]>
> Confirmed-by: Matthew Wilcox <[email protected]>
> Fixes: f3ba3c710ac5 ("mm/highmem: Provide kmap_local*")
> Signed-off-by: Fabio M. De Francesco <[email protected]>
> ---
>
> I have (at least) two problems with this patch...
>
> 1) checkpatch.pl complains about the use of the non-standard
> "Confirmed-by" tags. I don't know how else I can give credit to Helge
> and Matthew. However, this is not the first time that I see non-standard
> tags in patches applied upstream (I too had a non-standard
> "Analysed-by" tag in patch which fixes a SAC bug). Any objections?
>
> 2) I'm not sure whether or not the "Fixes" tag is appropriate in this
> patch. Can someone either confirm or deny it?
>
> include/linux/highmem-internal.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/highmem-internal.h
> b/include/linux/highmem-internal.h index 034b1106d022..e247c9ac4583 100644
> --- a/include/linux/highmem-internal.h
> +++ b/include/linux/highmem-internal.h
> @@ -200,7 +200,7 @@ static inline void *kmap_local_pfn(unsigned long pfn)
> static inline void __kunmap_local(const void *addr)
> {
> #ifdef ARCH_HAS_FLUSH_ON_KUNMAP
> - kunmap_flush_on_unmap(addr);
> + kunmap_flush_on_unmap(PTR_ALIGN_DOWN(addr, PAGE_SIZE));
> #endif
> }
>
> --
> 2.39.0
I just realized that I forgot to Cc Thomas Gleixner. Therefore, I think I'd
better add him to the list and resend this patch.
I'm doing it immediately, so please drop this.
Thanks,
Fabio