| Message ID | 20220724212523.13317-1-fmdefrancesco@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] fs: Call kmap_local_page() in copy_string_kernel() | expand |
On Sun, 24 Jul 2022 23:25:23 +0200, Fabio M. De Francesco wrote: > The use of kmap_atomic() is being deprecated in favor of kmap_local_page(). > > With kmap_local_page(), the mappings are per thread, CPU local and not > globally visible. Furthermore, the mappings can be acquired from any > context (including interrupts). > > Therefore, replace kmap_atomic() with kmap_local_page() in > copy_string_kernel(). Instead of open-coding local mapping + memcpy(), > use memcpy_to_page(). Delete a redundant call to flush_dcache_page(). > > [...] Applied to for-next/execve, thanks! [1/1] fs: Call kmap_local_page() in copy_string_kernel() https://git.kernel.org/kees/c/0ff95c390bc8
diff --git a/fs/exec.c b/fs/exec.c index d20cb09476f3..eed899188333 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -630,7 +630,6 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) unsigned int bytes_to_copy = min_t(unsigned int, len, min_not_zero(offset_in_page(pos), PAGE_SIZE)); struct page *page; - char *kaddr; pos -= bytes_to_copy; arg -= bytes_to_copy; @@ -639,11 +638,8 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) page = get_arg_page(bprm, pos, 1); if (!page) return -E2BIG; - kaddr = kmap_atomic(page); flush_arg_page(bprm, pos & PAGE_MASK, page); - memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy); - flush_dcache_page(page); - kunmap_atomic(kaddr); + memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy); put_arg_page(page); }
The use of kmap_atomic() is being deprecated in favor of kmap_local_page(). With kmap_local_page(), the mappings are per thread, CPU local and not globally visible. Furthermore, the mappings can be acquired from any context (including interrupts). Therefore, replace kmap_atomic() with kmap_local_page() in copy_string_kernel(). Instead of open-coding local mapping + memcpy(), use memcpy_to_page(). Delete a redundant call to flush_dcache_page(). Tested with xfstests on a QEMU/ KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Suggested-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> --- v1->v2: Instead of open-coding a local mapping + memcpy(), use memcpy_to_page() (thanks to Ira Weiny for his comment on v1). fs/exec.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)