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bh=OqgTZYxXv/xNrmSvb/jrSTI6+V6l0vurYjj+uVFpJnM=; b=IlkTbDScrHTPu/x+i7AOpVtg6teF1LgwjWNKInB07JSsjdz7dcxBamVs07xSB8dlmcwlsC iJIWGhuLRU18Mmd526P0Q6nvaqDHoB6YrfWb/Ncs/W6+SZVnE/6VUMz7lsbaU5Tc82cSZc bvfvSNeU9sp8d9gKeqOyEgr8vIRhp5szn/xiRUQZGeTN4NULgbFoUUjbiYEPTvW/roGJXf 0xmBbAK3P3XLGeyUnDQxDG3QuQpPzGHx5j1eGkbkHMmNwelTwDs8APoVKbu4xxt675CipS 1HOsBR5UcJ3bqS1aWMo3HVql511PHiin89av3brrxDffAf9GIeYLpXnh43MKnQ== Message-ID: <182bfb4f-e856-47d8-bc54-d419109cb4ac@cachyos.org> Date: Tue, 8 Apr 2025 15:52:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 10/17] mm: uninline the main body of vma_start_write() To: Lorenzo Stoakes , Christoph Hellwig Cc: Vlastimil Babka , Suren Baghdasaryan , akpm@linux-foundation.org, peterz@infradead.org, willy@infradead.org, liam.howlett@oracle.com, mhocko@suse.com, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, lokeshgidra@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, klarasmodin@gmail.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com References: <20241226170710.1159679-1-surenb@google.com> <20241226170710.1159679-11-surenb@google.com> <0d36fd53-b817-4bbd-ae38-af094bd301df@suse.cz> <40182b31-95ad-4825-9c0c-0127be1734a6@cachyos.org> <3f9f8a06-a044-4bce-a4e6-f17090cb3c0f@lucifer.local> Content-Language: en-US From: Eric Naim In-Reply-To: <3f9f8a06-a044-4bce-a4e6-f17090cb3c0f@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 021F11A0004 X-Stat-Signature: kg1763tqbnx9n1hsqxrg11ds8gxybuoq X-HE-Tag: 1744098774-709392 X-HE-Meta: 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 aGZddibe /b3QMD0Pf+F/z0hre7dp9GJ0BhlZ7N2rHOXwG1zBgFIZLsbVahvselcUdjALRwnuJlz09lN+moBGgf9Ab6dqlRqUOJmAYooJg+DmI8K2Jt3A30kUtVT+g3Nqun+auiGqWdgC4/34M1ha1b620TGykwqrm48fmWQfv+D8KXBmzn5LsfhVEBHKdfjynVWxaul2huRwUwtNbmMSLlfLFp37OgMFI1d7YPxNHpeZ4sXyYkBZYna5zeHnM937caln6RtGC05bjTamOpgLFpeWCEAAs+0DW0Aiw9ET/m05l2V427IupUU9Hy+tvNrnbe/dnJFfB6/Yj+ExBW48d0VQ= 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: List-Subscribe: List-Unsubscribe: On 4/8/25 14:25, Lorenzo Stoakes wrote: > On Mon, Apr 07, 2025 at 11:01:46PM -0700, Christoph Hellwig wrote: >> On Tue, Apr 08, 2025 at 12:39:25PM +0800, Eric Naim wrote: >>> The out-of-tree NVIDIA modules seem to rely on this symbol, is it possible to use EXPORT_SYMBOL() here instead of EXPORT_SYMBOL_GPL(), below is the modpost error: >> >> No. They don't have any business using this. > > What on _earth_ are they using this for? Is this just via the VMA flag > manipulation functions? If it's something else, it's an unintended use of this. > > Anyway, generally speaking - agreed, this is absolutely a no-go Eric. In my view > we simply should not be using EXPORT_SYMBOL() for _any_ new symbols whatsoever. > > Out-of-tree modules are simply a non-consideration for core mm code, this is a > GPL open source project. If I had my way we'd simply revoke _all_ > EXPORT_SYMBOL()'s, not add new ones. > >> >> In fact vma_start_write should not be exported at all, just the >> vm_flags_{set,clear,mod} helpers. > > Yup, I'd rather we just kept vma_start_write() mm-internal, though of course > kernel/fork.c (ugh) needs it (we could probably refactor that in some way to > avoid), and literally just the PPC arch (again maybe we can find a way round > that). > > Maybe one for me to look at actually... hmm. > > Anyway Eric - I wonder if this is simply the nvidia OOT driver doing a > vm_flags_...() call and then having an issue because the lock is uninlined now? > > I guess you are jut noticing this is breaking and don't know since - proprietary > code. This seems to be the case, upon looking a bit deeper it looks like the driver code is calling atleast one of vm_flags_set. I couldn't find any direct calls to {,__}vma_start_write at first and was bit confused. > > Anyway in this case, the OOT driver should just write some GPL wrapper code or > something here. Or better yet - make the driver open source :) Yeah, as obvious as it seems it doesn't happen on their open-sourced code :) Either way, I'm thankful for the replies. NVIDIA *should* have probably noticed this already and it would probably fixed in the next driver or two so I'll just let sleeping dogs lie. -- Regards, Eric