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Wed, 09 Dec 2020 17:12:54 -0800 (PST) MIME-Version: 1.0 References: <20201207081556.pwxmhgdxayzbofpi@lion.mk-sys.cz> <20201207225351.2liywqaxxtuezzw3@lion.mk-sys.cz> <20201209144628.GA3474@wp.pl> <20201209150826.GP7338@casper.infradead.org> <20201209155148.GA5552@wp.pl> <20201209180552.GA28692@infradead.org> <20201209223206.GA1935@home.goodmis.org> In-Reply-To: <20201209223206.GA1935@home.goodmis.org> From: Alexei Starovoitov Date: Wed, 9 Dec 2020 17:12:43 -0800 Message-ID: Subject: Re: [PATCH] mm/filemap: add static for function __add_to_page_cache_locked To: Steven Rostedt Cc: Christoph Hellwig , Stanislaw Gruszka , Matthew Wilcox , Michal Kubecek , Justin Forbes , bpf , Alex Shi , Andrew Morton , Souptick Joarder , Linux-MM , LKML , Alexei Starovoitov , Daniel Borkmann , Josef Bacik Content-Type: text/plain; charset="UTF-8" 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 Wed, Dec 9, 2020 at 2:32 PM Steven Rostedt wrote: > > On Wed, Dec 09, 2020 at 06:05:52PM +0000, Christoph Hellwig wrote: > > On Wed, Dec 09, 2020 at 04:51:48PM +0100, Stanislaw Gruszka wrote: > > > On Wed, Dec 09, 2020 at 03:08:26PM +0000, Matthew Wilcox wrote: > > > > On Wed, Dec 09, 2020 at 03:46:28PM +0100, Stanislaw Gruszka wrote: > > > > > 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). > > > > > > > > FWIW, I intend to do some consolidation/renaming in this area. I > > > > trust that will not be a problem? > > > > > > If it does not break anything, it will be not a problem ;-) > > > > > > It's possible that __add_to_page_cache_locked() can be a global symbol > > > with add_to_page_cache_lru() + add_to_page_cache_locked() being just > > > static/inline wrappers around it. > > > > So what happens to BTF if we change this area entirely? Your IDs > > sound like some kind of ABI to me, which is extremely scary. > > Is BTF becoming the new tracepoint? That is, random additions of things like: > > BTF_ID(func,__add_to_page_cache_locked) > > Like was done in commit 1e6c62a882155 ("bpf: Introduce sleepable BPF > programs") without any notification to the maintainers of the > __add_to_page_cache_locked code, will suddenly become an API? huh? what api/abi you're talking about?