From: Dave Hansen <dave.hansen@intel.com> To: Colin Cross <ccross@android.com> Cc: lkml <linux-kernel@vger.kernel.org>, Kyungmin Park <kmpark@infradead.org>, Christoph Hellwig <hch@infradead.org>, John Stultz <john.stultz@linaro.org>, Rob Landley <rob@landley.net>, Arnd Bergmann <arnd@arndb.de>, Andrew Morton <akpm@linux-foundation.org>, Cyrill Gorcunov <gorcunov@openvz.org>, David Rientjes <rientjes@google.com>, Davidlohr Bueso <dave@gnu.org>, Kees Cook <keescook@chromium.org>, Al Viro <viro@zeniv.linux.org.uk>, Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>, Michel Lespinasse <walken@google.com>, Rik van Riel <riel@redhat.com>, Konstantin Khlebnikov <khlebnikov@openvz.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Rusty Russell <rusty@rustcorp.com.au>, "Eric W. Biederman" <ebiederm@xmission.com>, Oleg Nesterov <oleg@redhat.com>, Srikar Dronamraju <srikar@linux.vnet.ibm.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>Mic Subject: Re: [PATCH] mm: add sys_madvise2 and MADV_NAME to name vmas Date: Wed, 10 Jul 2013 16:38:25 -0700 [thread overview] Message-ID: <51DDF071.5000309@intel.com> (raw) In-Reply-To: <CAMbhsRTio2mS=azWTxSdRdaZJRRf5FfMNoQUZmrFjkB7kv9LSQ@mail.gmail.com> On 07/10/2013 04:23 PM, Colin Cross wrote: > On Wed, Jul 10, 2013 at 4:08 PM, Dave Hansen <dave.hansen@intel.com> wrote: >> On 07/03/2013 06:31 PM, Colin Cross wrote: >>> @@ -289,6 +291,7 @@ struct vm_area_struct { >>> #ifdef CONFIG_NUMA >>> struct mempolicy *vm_policy; /* NUMA policy for the VMA */ >>> #endif >>> + struct vma_name *vm_name; >>> }; >> >> You could probably get rid of the extra pointer by unioning this with >> vm_file. They should not ever get used together. We would, however, >> have to transition away from checking vma->vm_file for "is this vma >> file-backed"? We are out of VM_* flag space which is a bummer. > > I considered trying to union with vm_file, but like you said the lack > of space in vm_flags makes it hard. I'd rather see 32 more bits "wasted" on new flags than a pointer that is used very rarely. > It would also prevent naming file > backed mappings, which is supported by this patch set. It's not > required by my primary use case, but it could be useful to have the > dynamic linker identify the various elf segments. That's stretching it a bit. :) Here's one more idea: instead of having a kernel pointer, let's let userspace hand the kernel a userspace address, and the kernel will hang on to it. Userspace is responsible for keeping it valid, kind of like ARGV[]. When the kernel goes to dump out the /proc/$pid/maps fields, it can do a copy_from_user() to get the string back out. If this fails, it can just go and treat it like a non-named VMA, or could output "userspace sucks". That way, the kernel isn't dealing with refcounting and allocating strings. It's got security concerns, just like /proc/$pid/cmdline since it'll let you dig around in another process's address space via /proc. But, I think they're manageable. Hey, doing that would even let you reuse vm_file. >=PAGE_OFFFSET means it's a file. <PAGE_OFFSET means it's an anonymous string. :) -- 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>
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com> To: Colin Cross <ccross@android.com> Cc: lkml <linux-kernel@vger.kernel.org>, Kyungmin Park <kmpark@infradead.org>, Christoph Hellwig <hch@infradead.org>, John Stultz <john.stultz@linaro.org>, Rob Landley <rob@landley.net>, Arnd Bergmann <arnd@arndb.de>, Andrew Morton <akpm@linux-foundation.org>, Cyrill Gorcunov <gorcunov@openvz.org>, David Rientjes <rientjes@google.com>, Davidlohr Bueso <dave@gnu.org>, Kees Cook <keescook@chromium.org>, Al Viro <viro@zeniv.linux.org.uk>, Hugh Dickins <hughd@google.com>, Mel Gorman <mgorman@suse.de>, Michel Lespinasse <walken@google.com>, Rik van Riel <riel@redhat.com>, Konstantin Khlebnikov <khlebnikov@openvz.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Rusty Russell <rusty@rustcorp.com.au>, "Eric W. Biederman" <ebiederm@xmission.com>, Oleg Nesterov <oleg@redhat.com>, Srikar Dronamraju <srikar@linux.vnet.ibm.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Michal Hocko <mhocko@suse.cz>, Anton Vorontsov <anton.vorontsov@linaro.org>, Pekka Enberg <penberg@kernel.org>, Shaohua Li <shli@fusionio.com>, Sasha Levin <sasha.levin@oracle.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Johannes Weiner <hannes@cmpxchg.org>, Ingo Molnar <mingo@kernel.org>, open@kvack.org, list@kvack.org, DOCUMENTATION <linux-doc@vger.kernel.org>open@kvack.orglist@kvack.org, MEMORY MANAGEMENT <linux-mm@kvack.org>, "open list:GENERIC INCLUDE/A..." <linux-arch@vger.kernel.org> Subject: Re: [PATCH] mm: add sys_madvise2 and MADV_NAME to name vmas Date: Wed, 10 Jul 2013 16:38:25 -0700 [thread overview] Message-ID: <51DDF071.5000309@intel.com> (raw) In-Reply-To: <CAMbhsRTio2mS=azWTxSdRdaZJRRf5FfMNoQUZmrFjkB7kv9LSQ@mail.gmail.com> On 07/10/2013 04:23 PM, Colin Cross wrote: > On Wed, Jul 10, 2013 at 4:08 PM, Dave Hansen <dave.hansen@intel.com> wrote: >> On 07/03/2013 06:31 PM, Colin Cross wrote: >>> @@ -289,6 +291,7 @@ struct vm_area_struct { >>> #ifdef CONFIG_NUMA >>> struct mempolicy *vm_policy; /* NUMA policy for the VMA */ >>> #endif >>> + struct vma_name *vm_name; >>> }; >> >> You could probably get rid of the extra pointer by unioning this with >> vm_file. They should not ever get used together. We would, however, >> have to transition away from checking vma->vm_file for "is this vma >> file-backed"? We are out of VM_* flag space which is a bummer. > > I considered trying to union with vm_file, but like you said the lack > of space in vm_flags makes it hard. I'd rather see 32 more bits "wasted" on new flags than a pointer that is used very rarely. > It would also prevent naming file > backed mappings, which is supported by this patch set. It's not > required by my primary use case, but it could be useful to have the > dynamic linker identify the various elf segments. That's stretching it a bit. :) Here's one more idea: instead of having a kernel pointer, let's let userspace hand the kernel a userspace address, and the kernel will hang on to it. Userspace is responsible for keeping it valid, kind of like ARGV[]. When the kernel goes to dump out the /proc/$pid/maps fields, it can do a copy_from_user() to get the string back out. If this fails, it can just go and treat it like a non-named VMA, or could output "userspace sucks". That way, the kernel isn't dealing with refcounting and allocating strings. It's got security concerns, just like /proc/$pid/cmdline since it'll let you dig around in another process's address space via /proc. But, I think they're manageable. Hey, doing that would even let you reuse vm_file. >=PAGE_OFFFSET means it's a file. <PAGE_OFFSET means it's an anonymous string. :) -- 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:[~2013-07-10 23:38 UTC|newest] Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-07-04 1:31 [PATCH] mm: add sys_madvise2 and MADV_NAME to name vmas Colin Cross 2013-07-04 1:31 ` Colin Cross 2013-07-04 4:54 ` Eric W. Biederman 2013-07-04 4:54 ` Eric W. Biederman 2013-07-04 6:32 ` Colin Cross 2013-07-04 6:32 ` Colin Cross 2013-07-05 16:52 ` Oleg Nesterov 2013-07-05 16:52 ` Oleg Nesterov 2013-07-06 6:33 ` Pekka Enberg 2013-07-06 6:33 ` Pekka Enberg 2013-07-06 11:53 ` Eric W. Biederman 2013-07-06 11:53 ` Eric W. Biederman 2013-07-07 18:35 ` Colin Cross 2013-07-07 18:35 ` Colin Cross 2013-07-14 1:38 ` Simon Jeons 2013-07-04 8:56 ` Peter Zijlstra 2013-07-04 8:56 ` Peter Zijlstra 2013-07-05 20:25 ` Colin Cross 2013-07-05 20:25 ` Colin Cross 2013-07-10 23:20 ` Dave Hansen 2013-07-10 23:20 ` Dave Hansen 2013-07-04 20:22 ` Oleg Nesterov 2013-07-04 20:22 ` Oleg Nesterov 2013-07-05 19:40 ` Colin Cross 2013-07-05 19:40 ` Colin Cross 2013-07-08 18:04 ` [PATCH 0/1] mm: mempolicy: (Was: add sys_madvise2 and MADV_NAME to name vmas) Oleg Nesterov 2013-07-08 18:04 ` Oleg Nesterov 2013-07-08 18:05 ` [PATCH 1/1] mm: mempolicy: fix mbind_range() && vma_adjust() interaction Oleg Nesterov 2013-07-08 18:05 ` Oleg Nesterov 2013-07-08 22:29 ` KOSAKI Motohiro 2013-07-08 22:29 ` KOSAKI Motohiro 2013-07-09 15:28 ` Oleg Nesterov 2013-07-09 15:28 ` Oleg Nesterov 2013-07-09 19:43 ` Oleg Nesterov 2013-07-09 19:43 ` Oleg Nesterov 2013-07-10 2:49 ` KOSAKI Motohiro 2013-07-10 2:49 ` KOSAKI Motohiro 2013-07-09 21:56 ` Andrew Morton 2013-07-09 21:56 ` Andrew Morton 2013-07-10 15:45 ` Oleg Nesterov 2013-07-10 15:45 ` Oleg Nesterov 2013-07-24 9:40 ` [PATCH] mm: add sys_madvise2 and MADV_NAME to name vmas Jan Glauber 2013-07-24 9:40 ` Jan Glauber 2013-07-24 20:05 ` Colin Cross 2013-07-24 20:05 ` Colin Cross 2013-07-10 23:08 ` Dave Hansen 2013-07-10 23:08 ` Dave Hansen [not found] ` <CAMbhsRTio2mS=azWTxSdRdaZJRRf5FfMNoQUZmrFjkB7kv9LSQ@mail.gmail.com> 2013-07-10 23:38 ` Dave Hansen [this message] 2013-07-10 23:38 ` Dave Hansen [not found] ` <CAMbhsRTs45QE1ze6mvdiL2QYKD0dHjXoRk7o1h2Y_rYP80ckDg@mail.gmail.com> 2013-07-11 0:19 ` Dave Hansen 2013-07-11 0:19 ` Dave Hansen
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