This is a note to let you know that I've just added the patch titled mm/error_inject: Fix allow_error_inject function signatures. to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-error_inject-fix-allow_error_inject-function-sign.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 86bea7fababae11e35ee868fc5630ad5cc5b18c9 Author: Alexei Starovoitov <ast@xxxxxxxxxx> Date: Thu Aug 27 15:01:10 2020 -0700 mm/error_inject: Fix allow_error_inject function signatures. [ Upstream commit 76cd61739fd107a7f7ec4c24a045e98d8ee150f0 ] 'static' and 'static noinline' function attributes make no guarantees that gcc/clang won't optimize them. The compiler may decide to inline 'static' function and in such case ALLOW_ERROR_INJECT becomes meaningless. The compiler could have inlined __add_to_page_cache_locked() in one callsite and didn't inline in another. In such case injecting errors into it would cause unpredictable behavior. It's worse with 'static noinline' which won't be inlined, but it still can be optimized. Like the compiler may decide to remove one argument or constant propagate the value depending on the callsite. To avoid such issues make sure that these functions are global noinline. Fixes: af3b854492f3 ("mm/page_alloc.c: allow error injection") Fixes: cfcbfb1382db ("mm/filemap.c: enable error injection at add_to_page_cache()") Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/bpf/20200827220114.69225-2-alexei.starovoitov@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/mm/filemap.c b/mm/filemap.c index 385759c4ce4be..6c3b879116212 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -826,10 +826,10 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) } EXPORT_SYMBOL_GPL(replace_page_cache_page); -static int __add_to_page_cache_locked(struct page *page, - struct address_space *mapping, - pgoff_t offset, gfp_t gfp_mask, - void **shadowp) +noinline int __add_to_page_cache_locked(struct page *page, + struct address_space *mapping, + pgoff_t offset, gfp_t gfp_mask, + void **shadowp) { XA_STATE(xas, &mapping->i_pages, offset); int huge = PageHuge(page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 43f6d91f57156..802f00540a3d2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3487,7 +3487,7 @@ static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) #endif /* CONFIG_FAIL_PAGE_ALLOC */ -static noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) +noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) { return __should_fail_alloc_page(gfp_mask, order); }