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b=gHiMeoWa0lzT85g1imdgbajsEHzGCaCYUlk/ONYUe6Zp7GrwM6LszSffkEbLgdXRr dHZltfJQaFh2HH5t9EAQ3UnL3Ixs52lRSxs09kbyRMkq2VD1ynpM5lHjNHH+VRSQRI VYoQuFvj+E/HihP+bWCJ+ELFTH2RSC3ESwGcFY+o= Date: Mon, 2 Sep 2024 13:49:53 -0700 From: Andrew Morton To: Sven Schnelle Cc: Nathan Chancellor , Michael Ellerman , linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, torvalds@linux-foundation.org, christophe.leroy@csgroup.eu, jeffxu@google.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, npiggin@gmail.com, oliver.sang@intel.com, pedro.falcato@gmail.com, linux-um@lists.infradead.org, linux-s390@vger.kernel.org, Ravi Bangoria , Steven Rostedt Subject: Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping Message-Id: <20240902134953.e834bc2e57d36b1d3b1397e4@linux-foundation.org> In-Reply-To: References: <20240812082605.743814-1-mpe@ellerman.id.au> <20240819185253.GA2333884@thelio-3990X> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: kcdmyfqmfs87tnopn96ey3qodoazuadi X-Rspamd-Queue-Id: 58F484000B X-Rspamd-Server: rspam11 X-HE-Tag: 1725310196-973935 X-HE-Meta: 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 XcXFzf2Z C7eK3XpVwidzIBcsTltU3SIR2Xijni3n42doSy/P6p782EMMyRKgHxY5WIK7dLHCBu1JgU6hWMi7ISS7nl71Foe0HTaZqkcsBZPQZkpFTk9N4ZUXwAwY+9hoJ10NA522Mt+uVS5qH+kW1LnFK1BqZ9uPUk06xq6v8qqzdscv9Kw9F+3b0I5GEyIHcNSoSCqfIb46L8aXF760Sr6acCoKNz2rbti4sDkkI+DokLvIUYAEVXHA1D0VQRZHJ3wR8MZBR7QaKobq0bEHanio5Bt0NXnGTLONRluyTLu8gdg4cOZZKzoGLQBEsMDQYv/WDbXYcBWVDkAt1cWje9U09MjEOrfw3sV7ZxOQ1WyWAEXIbRF+3t8r/17lbVBEiJw== 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 Mon, 02 Sep 2024 21:06:48 +0200 Sven Schnelle wrote: > So uprobe_clear_state() in the beginning free's the memory area > containing the vm_special_mapping data, but exit_mmap() uses this > address later via vma->vm_private_data (which was set in _install_special_mapping(). > > The following change fixes this for me, but i'm not sure about any side > effects: > > diff --git a/kernel/fork.c b/kernel/fork.c > index df8e4575ff01..cfcabba36c93 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1340,11 +1340,11 @@ static inline void __mmput(struct mm_struct *mm) > { > VM_BUG_ON(atomic_read(&mm->mm_users)); > > - uprobe_clear_state(mm); > exit_aio(mm); > ksm_exit(mm); > khugepaged_exit(mm); /* must run before exit_mmap */ > exit_mmap(mm); > + uprobe_clear_state(mm); > mm_put_huge_zero_folio(mm); > set_mm_exe_file(mm, NULL); > if (!list_empty(&mm->mmlist)) { uprobe_clear_state() is a pretty simple low-level thing. Side-effects seem unlikely?