On Mon, Dec 07, 2020 at 05:12:52PM -0800, Alexei Starovoitov wrote: > > > > > > > >>> -noinline int __add_to_page_cache_locked(struct page *page, > > > > > > > >>> +static noinline int __add_to_page_cache_locked(struct page *page, > > > > > > > >>> struct address_space *mapping, > > > > > > > >>> pgoff_t offset, gfp_t gfp, > > > > > > > >>> void **shadowp) > > > > > > > > > > > > > > > > It's unclear to me whether BTF_ID() requires that the target symbol be > > > > > > > > non-static. It doesn't actually reference the symbol: > > > > > > > > > > > > > > > > #define BTF_ID(prefix, name) \ > > > > > > > > __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__)) [snip] > > > __add_to_page_cache_locked") made the function static which breaks the > > > build in btfids phase - but it seems to happen only on some > > > architectures. In our case, ppc64, ppc64le and riscv64 are broken, > > > x86_64, i586 and s390x succeed. (I made a mistake above, aarch64 did not > > > fail - but only because it was not built at all.) > > > > > > The thread starts with > > > http://lkml.kernel.org/r/1604661895-5495-1-git-send-email-alex.shi@xxxxxxxxxxxxxxxxx I have 5.10-rc7 build failure because of this on x86_64: BTFIDS vmlinux FAILED unresolved symbol __add_to_page_cache_locked make: *** [Makefile:1170: vmlinux] Error 255 > > Got it. So the above commit is wrong. > > The addition of "static" is incorrect here. > > Regardless of btf_id generation. > > "static noinline" means that the error injection in that spot is unreliable. > > Even when bpf is completely compiled out of the kernel. > > I finally realized that the addition of 'static' was pushed into Linus's tree :( > Please revert commit 3351b16af494 ("mm/filemap: add static for > function __add_to_page_cache_locked") At this point of release cycle we should probably go with revert, but I think the main problem is that BPF and ERROR_INJECTION use function that is not intended to be used externally. For external users add_to_page_cache_lru() and add_to_page_cache_locked() are exported and I think those should be used (see the patch below). Stanislaw diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1388bf733071..dd6357802504 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11487,7 +11487,8 @@ BTF_SET_START(btf_non_sleepable_error_inject) /* Three functions below can be called from sleepable and non-sleepable context. * Assume non-sleepable from bpf safety point of view. */ -BTF_ID(func, __add_to_page_cache_locked) +BTF_ID(func, add_to_page_cache_locked) +BTF_ID(func, add_to_page_cache_lru) BTF_ID(func, should_fail_alloc_page) BTF_ID(func, should_failslab) BTF_SET_END(btf_non_sleepable_error_inject) diff --git a/mm/filemap.c b/mm/filemap.c index 331f4261d723..168deec64a10 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -827,10 +827,10 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) } EXPORT_SYMBOL_GPL(replace_page_cache_page); -static noinline int __add_to_page_cache_locked(struct page *page, - struct address_space *mapping, - pgoff_t offset, gfp_t gfp, - void **shadowp) +static int __add_to_page_cache_locked(struct page *page, + struct address_space *mapping, + pgoff_t offset, gfp_t gfp, + void **shadowp) { XA_STATE(xas, &mapping->i_pages, offset); int huge = PageHuge(page); @@ -907,7 +907,6 @@ static noinline int __add_to_page_cache_locked(struct page *page, put_page(page); return error; } -ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO); /** * add_to_page_cache_locked - add a locked page to the pagecache @@ -928,6 +927,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, gfp_mask, NULL); } EXPORT_SYMBOL(add_to_page_cache_locked); +ALLOW_ERROR_INJECTION(add_to_page_cache_locked, ERRNO); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) @@ -957,6 +957,7 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping, return ret; } EXPORT_SYMBOL_GPL(add_to_page_cache_lru); +ALLOW_ERROR_INJECTION(add_to_page_cache_lru, ERRNO); #ifdef CONFIG_NUMA struct page *__page_cache_alloc(gfp_t gfp)
