From: Christoph Hellwig hch@lst.de
commit 8dad53a11f8d94dceb540a5f8f153484f42be84b upstream.
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.
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 driver, 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.
Link: https://lkml.kernel.org/r/20210713055231.137602-2-hch@lst.de 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 Cc: Chaitanya Kulkarni chaitanya.kulkarni@wdc.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/highmem.h | 2 ++ 1 file changed, 2 insertions(+)
--- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -329,6 +329,7 @@ static inline void memcpy_to_page(struct
VM_BUG_ON(offset + len > PAGE_SIZE); memcpy(to + offset, from, len); + flush_dcache_page(page); kunmap_local(to); }
@@ -336,6 +337,7 @@ static inline void memzero_page(struct p { char *addr = kmap_atomic(page); memset(addr + offset, 0, len); + flush_dcache_page(page); kunmap_atomic(addr); }