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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: 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: >>=20 >>> On Fri, Nov 6, 2020 at 4:55 PM Alex Shi wr= ote: >>>> >>>> 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-prototypes] >>>> noinline int __add_to_page_cache_locked(struct page *page, >>>> ^~~~~~~~~~~~~~~~~~~~~~~~~~ >>> >>> Is CONFIG_DEBUG_INFO_BTF enabled in your .config ? >>=20 >> hm, yes. > > When the config enabled, compiling looks good untill pahole tool > used to get BTF info, but I still failed on a right version pahole >> 1.16. Sorry. I'm seeing an issue with this patch. My build system has pahole v1.17, but I don't think the pahole version is key. $ git checkout 3351b16af494 # recently added to linus/master $ make defconfig $ make menuconfig # set CONFIG_BPF_SYSCALL and CONFIG_DEBUG_INFO_BTF $ make V=3D1 + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux FAILED unresolved symbol __add_to_page_cache_locked Reverting 3351b16af494 ("mm/filemap: add static for function __add_to_page_cache_locked") fixes the issue. I don't see the warning which motivated this patch, but maybe it requires particular a .config or gcc version. Perhaps adding a __add_to_page_cache_locked() prototype would meet avoid it. But I haven't studied enough on BTF to know if there's a better answer. >>>> 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, stru= ct 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_space *mapping, >>>> pgoff_t offset, gfp_t gfp, >>>> void **shadowp) >>=20 >> It's unclear to me whether BTF_ID() requires that the target symbol be >> non-static. It doesn't actually reference the symbol: >>=20 >> #define BTF_ID(prefix, name) \ >> __BTF_ID(__ID(__BTF_ID__##prefix##__##name##__)) >>=20 > > The above usage make me thought BTF don't require the symbol, though > the symbol still exist in vmlinux with 'static'. > > So any comments of this, Alexei?=20 > >> Alexei, can you please comment? >>=20