| Message ID | 20210713055231.137602-2-hch@lst.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] mm: call flush_dcache_page in memcpy_to_page and memzero_page | expand |
On Tue, 13 Jul 2021 07:52:30 +0200 Christoph Hellwig <hch@lst.de> wrote: > memcpy_to_page and memzero_page can write to arbitrary pages, which could > be in the page cache or in high memory, so call flush_kernel_dcache_pages > to flush the dcache. I assume this presently is not known to cause any problems, but that some problems might be discovered in the future? In which case, should we cc:stable?
On Tue, Jul 13, 2021 at 06:31:23PM -0700, Andrew Morton wrote: > On Tue, 13 Jul 2021 07:52:30 +0200 Christoph Hellwig <hch@lst.de> wrote: > > > memcpy_to_page and memzero_page can write to arbitrary pages, which could > > be in the page cache or in high memory, so call flush_kernel_dcache_pages > > to flush the dcache. > > I assume this presently is not known to cause any problems, but that > some problems might be discovered in the future? In which case, > should we cc:stable? This is a problem when using these helpers on dcache challeneged architectures. Right now there are just a few users, chances are no one used the PC floppy drŅver, the aha1542 driver for an ISA SCSI HBA, and a few advanced and optional btrfs and ext4 features on those platforms yet since the conversion. So yes, stable would be good.
On Tue, Jul 13, 2021 at 07:52:30AM +0200, Christoph Hellwig wrote: > memcpy_to_page and memzero_page can write to arbitrary pages, which could > be in the page cache or in high memory, so call flush_kernel_dcache_pages > to flush the dcache. > > Fixes: bb90d4bc7b6a ("mm/highmem: Lift memcpy_[to|from]_page to core") > Fixes: 28961998f858 ("iov_iter: lift memzero_page() to highmem.h") > Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ira Weiny <ira.weiny@intel.com> > --- > include/linux/highmem.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/include/linux/highmem.h b/include/linux/highmem.h > index 8c6e8e996c87..8e7e50a53a12 100644 > --- a/include/linux/highmem.h > +++ b/include/linux/highmem.h > @@ -318,6 +318,7 @@ static inline void memcpy_to_page(struct page *page, size_t offset, > > VM_BUG_ON(offset + len > PAGE_SIZE); > memcpy(to + offset, from, len); > + flush_dcache_page(page); > kunmap_local(to); > } > > @@ -325,6 +326,7 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len) > { > char *addr = kmap_atomic(page); > memset(addr + offset, 0, len); > + flush_dcache_page(page); > kunmap_atomic(addr); > } > > -- > 2.30.2 >
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 8c6e8e996c87..8e7e50a53a12 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -318,6 +318,7 @@ static inline void memcpy_to_page(struct page *page, size_t offset, VM_BUG_ON(offset + len > PAGE_SIZE); memcpy(to + offset, from, len); + flush_dcache_page(page); kunmap_local(to); } @@ -325,6 +326,7 @@ static inline void memzero_page(struct page *page, size_t offset, size_t len) { char *addr = kmap_atomic(page); memset(addr + offset, 0, len); + flush_dcache_page(page); kunmap_atomic(addr); }
memcpy_to_page and memzero_page can write to arbitrary pages, which could be in the page cache or in high memory, so call flush_kernel_dcache_pages to flush the dcache. Fixes: bb90d4bc7b6a ("mm/highmem: Lift memcpy_[to|from]_page to core") Fixes: 28961998f858 ("iov_iter: lift memzero_page() to highmem.h") Signed-off-by: Christoph Hellwig <hch@lst.de> --- include/linux/highmem.h | 2 ++ 1 file changed, 2 insertions(+)