From: David Laight <David.Laight@ACULAB.COM> To: "'Michael Ellerman'" <mpe@ellerman.id.au>, Matthew Wilcox <willy@infradead.org>, Kees Cook <keescook@chromium.org> Cc: Cyril Hrubis <chrubis@suse.cz>, Michal Hocko <mhocko@kernel.org>, "Linux API" <linux-api@vger.kernel.org>, Khalid Aziz <khalid.aziz@oracle.com>, "Andrew Morton" <akpm@linux-foundation.org>, Russell King - ARM Linux <linux@armlinux.org.uk>, Andrea Arcangeli <aarcange@redhat.com>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, linux-arch <linux-arch@vger.kernel.org>, Florian Weimer <fweimer@redhat.com>, "John Hubbard" <jhubbard@nvidia.com>, Abdul Haleem <abdhalee@linux.vnet.ibm.com>, Joel Stanley <joel@jms.id.au>, Pavel Machek <pavel@ucw.cz> Subject: RE: [PATCH 0/2] mm: introduce MAP_FIXED_SAFE Date: Fri, 8 Dec 2017 14:33:35 +0000 [thread overview] Message-ID: <0b0bd6862e3a47728c8f658c8a6b3dea@AcuMS.aculab.com> (raw) In-Reply-To: <87shclh3zc.fsf@concordia.ellerman.id.au> From: Michael Ellerman > Sent: 08 December 2017 11:08 ... > If we had a time machine, the right set of flags would be: > > - MAP_FIXED: don't treat addr as a hint, fail if addr is not free > - MAP_REPLACE: replace an existing mapping (or force or clobber) > > But the two were conflated for some reason in the current MAP_FIXED. Possibly because the original use was loading overlays? > Given we can't go back and fix it, the closest we can get is to add a > variant of MAP_FIXED which subtracts the "REPLACE" semantic. > > ie: MAP_FIXED_NOREPLACE Much better than _SAFE - which is always bad because it is usually one 'safe' for one specific use case. David
WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM> To: 'Michael Ellerman' <mpe@ellerman.id.au>, Matthew Wilcox <willy@infradead.org>, Kees Cook <keescook@chromium.org> Cc: Cyril Hrubis <chrubis@suse.cz>, Michal Hocko <mhocko@kernel.org>, Linux API <linux-api@vger.kernel.org>, Khalid Aziz <khalid.aziz@oracle.com>, Andrew Morton <akpm@linux-foundation.org>, Russell King - ARM Linux <linux@armlinux.org.uk>, Andrea Arcangeli <aarcange@redhat.com>, Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, linux-arch <linux-arch@vger.kernel.org>, Florian Weimer <fweimer@redhat.com>, John Hubbard <jhubbard@nvidia.com>, Abdul Haleem <abdhalee@linux.vnet.ibm.com>, Joel Stanley <joel@jms.id.au>, Pavel Machek <pavel@ucw.cz> Subject: RE: [PATCH 0/2] mm: introduce MAP_FIXED_SAFE Date: Fri, 8 Dec 2017 14:33:35 +0000 [thread overview] Message-ID: <0b0bd6862e3a47728c8f658c8a6b3dea@AcuMS.aculab.com> (raw) In-Reply-To: <87shclh3zc.fsf@concordia.ellerman.id.au> From: Michael Ellerman > Sent: 08 December 2017 11:08 ... > If we had a time machine, the right set of flags would be: > > - MAP_FIXED: don't treat addr as a hint, fail if addr is not free > - MAP_REPLACE: replace an existing mapping (or force or clobber) > > But the two were conflated for some reason in the current MAP_FIXED. Possibly because the original use was loading overlays? > Given we can't go back and fix it, the closest we can get is to add a > variant of MAP_FIXED which subtracts the "REPLACE" semantic. > > ie: MAP_FIXED_NOREPLACE Much better than _SAFE - which is always bad because it is usually one 'safe' for one specific use case. David -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-12-08 14:33 UTC|newest] Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-11-29 14:42 [PATCH 0/2] mm: introduce MAP_FIXED_SAFE Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-11-29 14:42 ` [PATCH 1/2] " Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-12-06 5:15 ` Michael Ellerman 2017-12-06 5:15 ` Michael Ellerman 2017-12-06 9:27 ` Michal Hocko 2017-12-06 9:27 ` Michal Hocko 2017-12-06 10:02 ` Michal Hocko 2017-12-06 10:02 ` Michal Hocko 2017-12-07 12:07 ` Pavel Machek 2017-12-07 12:07 ` Pavel Machek 2017-11-29 14:42 ` [PATCH 2/2] fs, elf: drop MAP_FIXED usage from elf_map Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-11-29 14:42 ` Michal Hocko 2017-11-29 17:45 ` Khalid Aziz 2017-11-29 17:45 ` Khalid Aziz 2018-05-29 22:21 ` Mike Kravetz 2018-05-30 8:02 ` Michal Hocko 2018-05-30 15:00 ` Mike Kravetz 2018-05-30 16:25 ` Michal Hocko 2018-05-31 0:51 ` Mike Kravetz 2018-05-31 9:24 ` Michal Hocko 2018-05-31 21:46 ` Mike Kravetz 2017-11-29 14:45 ` [PATCH] mmap.2: document new MAP_FIXED_SAFE flag Michal Hocko 2017-11-29 14:45 ` Michal Hocko 2017-11-29 14:45 ` Michal Hocko 2017-11-30 3:16 ` John Hubbard 2017-11-30 3:16 ` John Hubbard 2017-11-30 3:16 ` John Hubbard 2017-11-30 8:23 ` Michal Hocko 2017-11-30 8:23 ` Michal Hocko 2017-11-30 8:24 ` [PATCH v2] " Michal Hocko 2017-11-30 8:24 ` Michal Hocko 2017-11-30 8:24 ` Michal Hocko 2017-11-30 8:24 ` Michal Hocko 2017-11-30 18:31 ` John Hubbard 2017-11-30 18:31 ` John Hubbard 2017-11-30 18:31 ` John Hubbard 2017-11-30 18:39 ` Michal Hocko 2017-11-30 18:39 ` Michal Hocko 2017-11-29 15:13 ` [PATCH 0/2] mm: introduce MAP_FIXED_SAFE Rasmus Villemoes 2017-11-29 15:13 ` Rasmus Villemoes 2017-11-29 15:13 ` Rasmus Villemoes 2017-11-29 15:50 ` Michal Hocko 2017-11-29 15:50 ` Michal Hocko 2017-11-29 15:50 ` Michal Hocko 2017-11-29 22:15 ` Kees Cook 2017-11-29 22:15 ` Kees Cook 2017-11-29 22:12 ` Kees Cook 2017-11-29 22:12 ` Kees Cook 2017-11-29 22:25 ` Kees Cook 2017-11-29 22:25 ` Kees Cook 2017-11-30 6:58 ` Michal Hocko 2017-11-30 6:58 ` Michal Hocko 2017-11-30 6:58 ` Michal Hocko 2017-12-01 15:26 ` Cyril Hrubis 2017-12-01 15:26 ` Cyril Hrubis 2017-12-06 4:51 ` Michael Ellerman 2017-12-06 4:51 ` Michael Ellerman 2017-12-06 4:54 ` Matthew Wilcox 2017-12-06 4:54 ` Matthew Wilcox 2017-12-06 7:03 ` Matthew Wilcox 2017-12-06 7:03 ` Matthew Wilcox 2017-12-06 7:33 ` John Hubbard 2017-12-06 7:33 ` John Hubbard 2017-12-06 7:35 ` Florian Weimer 2017-12-06 7:35 ` Florian Weimer 2017-12-06 7:35 ` Florian Weimer 2017-12-06 8:06 ` John Hubbard 2017-12-06 8:06 ` John Hubbard 2017-12-06 8:06 ` John Hubbard 2017-12-06 8:06 ` John Hubbard 2017-12-06 8:54 ` Florian Weimer 2017-12-06 8:54 ` Florian Weimer 2017-12-06 8:54 ` Florian Weimer 2017-12-07 5:46 ` Michael Ellerman 2017-12-07 5:46 ` Michael Ellerman 2017-12-07 5:46 ` Michael Ellerman 2017-12-07 19:14 ` Kees Cook 2017-12-07 19:14 ` Kees Cook 2017-12-07 19:57 ` Matthew Wilcox 2017-12-07 19:57 ` Matthew Wilcox 2017-12-07 19:57 ` Matthew Wilcox 2017-12-08 8:33 ` Michal Hocko 2017-12-08 8:33 ` Michal Hocko 2017-12-08 20:13 ` Kees Cook 2017-12-08 20:13 ` Kees Cook 2017-12-08 20:13 ` Kees Cook 2017-12-08 20:57 ` Matthew Wilcox 2017-12-08 20:57 ` Matthew Wilcox 2017-12-08 20:57 ` Matthew Wilcox 2017-12-08 11:08 ` Michael Ellerman 2017-12-08 11:08 ` Michael Ellerman 2017-12-08 14:27 ` Pavel Machek 2017-12-08 20:31 ` Cyril Hrubis 2017-12-08 20:31 ` Cyril Hrubis 2017-12-08 20:31 ` Cyril Hrubis 2017-12-08 20:47 ` Florian Weimer 2017-12-08 20:47 ` Florian Weimer 2017-12-08 20:47 ` Florian Weimer 2017-12-08 14:33 ` David Laight [this message] 2017-12-08 14:33 ` David Laight 2017-12-06 4:50 ` Michael Ellerman 2017-12-06 4:50 ` Michael Ellerman 2017-12-06 7:33 ` Rasmus Villemoes 2017-12-06 7:33 ` Rasmus Villemoes 2017-12-06 7:33 ` Rasmus Villemoes 2017-12-06 9:08 ` Michal Hocko 2017-12-06 9:08 ` Michal Hocko 2017-12-06 9:08 ` Michal Hocko 2017-12-07 0:19 ` Kees Cook 2017-12-07 0:19 ` Kees Cook 2017-12-07 1:08 ` John Hubbard 2017-12-07 1:08 ` John Hubbard
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