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Date: Mon, 9 Mar 2020 20:03:46 +0000 From: Bernd Edlinger <bernd.edlinger@...mail.de> To: "Eric W. Biederman" <ebiederm@...ssion.com> CC: Christian Brauner <christian.brauner@...ntu.com>, Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>, Alexander Viro <viro@...iv.linux.org.uk>, Andrew Morton <akpm@...ux-foundation.org>, Alexey Dobriyan <adobriyan@...il.com>, Thomas Gleixner <tglx@...utronix.de>, Oleg Nesterov <oleg@...hat.com>, Frederic Weisbecker <frederic@...nel.org>, Andrei Vagin <avagin@...il.com>, Ingo Molnar <mingo@...nel.org>, "Peter Zijlstra (Intel)" <peterz@...radead.org>, Yuyang Du <duyuyang@...il.com>, David Hildenbrand <david@...hat.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Anshuman Khandual <anshuman.khandual@....com>, David Howells <dhowells@...hat.com>, James Morris <jamorris@...ux.microsoft.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Shakeel Butt <shakeelb@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>, Christian Kellner <christian@...lner.me>, Andrea Arcangeli <aarcange@...hat.com>, Aleksa Sarai <cyphar@...har.com>, "Dmitry V. Levin" <ldv@...linux.org>, "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "stable@...r.kernel.org" <stable@...r.kernel.org>, "linux-api@...r.kernel.org" <linux-api@...r.kernel.org> Subject: Re: [PATCH v2 4/5] exec: Move exec_mmap right after de_thread in flush_old_exec On 3/9/20 8:58 PM, Eric W. Biederman wrote: > > Ok. I think this has it sorted: > > exec: Move exec_mmap right after de_thread in flush_old_exec > > I have read through the code in exec_mmap and I do not see anything > that depends on sighand or the sighand lock, or on signals in anyway > so this should be safe. > > This rearrangement of code has two significant benefits. It makes > the determination of passing the point of no return by testing bprm->mm > accurate. All failures prior to that point in flush_old_exec are > either truly recoverable or they are fatal. > > Further this consolidates all of the possible indefinite waits for > userspace together at the top of flush_old_exec. The possible wait > for a ptracer on PTRACE_EVENT_EXIT, the possible wait for a page fault > to be resolved in clear_child_tid, and the possible wait for a page > fault in exit_robust_list. > > This consolidation allows the creation of a mutex to replace > cred_guard_mutex that is not held over possible indefinite userspace > waits. Which will allow removing deadlock scenarios from the kernel. > > Reviewed-by: Bernd Edlinger <bernd.edlinger@...mail.de> > Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com> > > > I don't think I usually have this many typos. Sigh. > OK. never mind, Bernd.
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