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Groups > linux.kernel > #1212211
| From | Konstantin Khlebnikov <koct9i@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT |
| Date | 2015-08-24 16:00 +0200 |
| Message-ID | <q10s2-14H-13@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <pZBvJ-2L0-23@gated-at.bofh.it> <pZOVZ-5dT-21@gated-at.bofh.it> <pZZom-3ny-5@gated-at.bofh.it> <q0X18-4Km-23@gated-at.bofh.it> <q108G-Hc-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, Aug 24, 2015 at 4:30 PM, Vlastimil Babka <vbabka@suse.cz> wrote: > On 08/24/2015 12:17 PM, Konstantin Khlebnikov wrote: >>> >>> >>> I am in the middle of implementing lock on fault this way, but I cannot >>> see how we will hanlde mremap of a lock on fault region. Say we have >>> the following: >>> >>> addr = mmap(len, MAP_ANONYMOUS, ...); >>> mlock(addr, len, MLOCK_ONFAULT); >>> ... >>> mremap(addr, len, 2 * len, ...) >>> >>> There is no way for mremap to know that the area being remapped was lock >>> on fault so it will be locked and prefaulted by remap. How can we avoid >>> this without tracking per vma if it was locked with lock or lock on >>> fault? >> >> >> remap can count filled ptes and prefault only completely populated areas. > > > Does (and should) mremap really prefault non-present pages? Shouldn't it > just prepare the page tables and that's it? As I see mremap prefaults pages when it extends mlocked area. Also quote from manpage : If the memory segment specified by old_address and old_size is locked : (using mlock(2) or similar), then this lock is maintained when the segment is : resized and/or relocated. As a consequence, the amount of memory locked : by the process may change. > >> There might be a problem after failed populate: remap will handle them >> as lock on fault. In this case we can fill ptes with swap-like non-present >> entries to remember that fact and count them as should-be-locked pages. > > > I don't think we should strive to have mremap try to fix the inherent > unreliability of mmap (MAP_POPULATE)? I don't think so. MAP_POPULATE works only when mmap happens. Flag MREMAP_POPULATE might be a good idea. Just for symmetry. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-19 23:40 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-20 10:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-20 19:10 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-21 09:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-21 20:40 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-24 12:20 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Vlastimil Babka <vbabka@suse.cz> - 2015-08-24 15:40 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-24 16:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Vlastimil Babka <vbabka@suse.cz> - 2015-08-24 16:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-24 17:10 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-24 17:50 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-24 18:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-24 18:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-24 19:10 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-24 21:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-24 22:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-25 15:50 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Vlastimil Babka <vbabka@suse.cz> - 2015-08-25 16:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-25 16:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Konstantin Khlebnikov <koct9i@gmail.com> - 2015-08-25 16:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-25 16:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-25 21:00 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Eric B Munson <emunson@akamai.com> - 2015-08-25 21:10 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Michal Hocko <mhocko@kernel.org> - 2015-08-26 09:30 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Vlastimil Babka <vbabka@suse.cz> - 2015-08-26 17:40 +0200
Re: [PATCH v7 3/6] mm: Introduce VM_LOCKONFAULT Vlastimil Babka <vbabka@suse.cz> - 2015-08-20 10:00 +0200
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