From mboxrd@z Thu Jan 1 00:00:00 1970 From: kanoj@google.engr.sgi.com (Kanoj Sarcar) Message-Id: <199910131834.LAA38192@google.engr.sgi.com> Subject: Re: [more fun] Re: locking question: do_mmap(), do_munmap() Date: Wed, 13 Oct 1999 11:34:32 -0700 (PDT) In-Reply-To: <38043651.FA0BA70E@colorfullife.com> from "Manfred Spraul" at Oct 13, 99 09:35:45 am MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Manfred Spraul Cc: viro@math.psu.edu, sct@redhat.com, andrea@suse.de, linux-kernel@vger.rutgers.edu, mingo@chiara.csoma.elte.hu, torvalds@transmeta.com, linux-mm@kvack.org List-ID: > > Alexander Viro wrote: > > Another one: ptrace_readdata() -> access_process_vm() -> find_extend_vma() > > -> make_pages_present(). Again, no mmap_sem in sight. Actually, I think access_process_vm() does get mmap_sem, although after doing the find_extend_vma, which should be fixed. I will take care of it in my patch. > > Can 2 processes ptrace() each other? If yes, then this will lock-up if > you acquire the mmap_sem. > Theoretically, there is no problem with 2 processes ptrace()ing each other. IMO, no deadlock is possible in the approach I posted. Kanoj > -- > Manfred > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://humbolt.geo.uu.nl/Linux-MM/ > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/