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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Dec 7, 2020 at 2:59 PM Alexei Starovoitov wrote: > > On Mon, Dec 7, 2020 at 2:53 PM Michal Kubecek wrote: > > > > On Mon, Dec 07, 2020 at 02:44:22PM -0800, Alexei Starovoitov wrote: > > > On Mon, Dec 7, 2020 at 10:36 AM Justin Forbes = wrote: > > > > > > > > On Mon, Dec 7, 2020 at 2:16 AM Michal Kubecek wr= ote: > > > > > > > > > > On Thu, Nov 12, 2020 at 08:18:57AM +0800, Alex Shi wrote: > > > > > > > > > > > > > > > > > > =E5=9C=A8 2020/11/11 =E4=B8=8A=E5=8D=883:50, Andrew Morton =E5= =86=99=E9=81=93: > > > > > > > On Tue, 10 Nov 2020 08:39:24 +0530 Souptick Joarder wrote: > > > > > > > > > > > > > >> On Fri, Nov 6, 2020 at 4:55 PM Alex Shi wrote: > > > > > > >>> > > > > > > >>> Otherwise it cause gcc warning: > > > > > > >>> ^~~~~~~~~~~~~~~ > > > > > > >>> ../mm/filemap.c:830:14: warning: no previous prototype for > > > > > > >>> =E2=80=98__add_to_page_cache_locked=E2=80=99 [-Wmissing-pro= totypes] > > > > > > >>> noinline int __add_to_page_cache_locked(struct page *page, > > > > > > >>> ^~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > > > >> > > > > > > >> Is CONFIG_DEBUG_INFO_BTF enabled in your .config ? > > > > > > > > > > > > > > hm, yes. > > > > > > > > > > > > When the config enabled, compiling looks good untill pahole too= l > > > > > > used to get BTF info, but I still failed on a right version pah= ole > > > > > > > 1.16. Sorry. > > > > > > > > > > > > > > > > > > > >>> > > > > > > >>> Signed-off-by: Alex Shi > > > > > > >>> Cc: Andrew Morton > > > > > > >>> Cc: linux-mm@kvack.org > > > > > > >>> Cc: linux-kernel@vger.kernel.org > > > > > > >>> --- > > > > > > >>> mm/filemap.c | 2 +- > > > > > > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > >>> > > > > > > >>> diff --git a/mm/filemap.c b/mm/filemap.c > > > > > > >>> index d90614f501da..249cf489f5df 100644 > > > > > > >>> --- a/mm/filemap.c > > > > > > >>> +++ b/mm/filemap.c > > > > > > >>> @@ -827,7 +827,7 @@ int replace_page_cache_page(struct page= *old, struct page *new, gfp_t gfp_mask) > > > > > > >>> } > > > > > > >>> EXPORT_SYMBOL_GPL(replace_page_cache_page); > > > > > > >>> > > > > > > >>> -noinline int __add_to_page_cache_locked(struct page *page, > > > > > > >>> +static noinline int __add_to_page_cache_locked(struct page= *page, > > > > > > >>> struct address_spac= e *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##__)) > > > > > > > > > > > > > > > > > > > The above usage make me thought BTF don't require the symbol, t= hough > > > > > > the symbol still exist in vmlinux with 'static'. > > > > > > > > > > > > So any comments of this, Alexei? > > > > > > Sorry. I've completely missed this thread. > > > Now I have a hard time finding context in archives. > > > If I understood what's going on the removal of "static" cases issues? > > > Yes. That's expected. > > > noinline alone is not enough to work reliably. > > > > Not removal, commit 3351b16af494 ("mm/filemap: add static for function > > __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 no= t > > 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@linu= x.alibaba.com > > 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 unreliab= le. > Even when bpf is completely compiled out of the kernel. I finally realized that the addition of 'static' was pushed into Linus's tr= ee :( Please revert commit 3351b16af494 ("mm/filemap: add static for function __add_to_page_cache_locked")