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e4a0d3e720
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Pavel Emelyanov e4a0d3e720 aio: Make it possible to remap aio ring 
There are actually two issues this patch addresses. Let me start with
the one I tried to solve in the beginning.

So, in the checkpoint-restore project (criu) we try to dump tasks'
state and restore one back exactly as it was. One of the tasks' state
bits is rings set up with io_setup() call. There's (almost) no problems
in dumping them, there's a problem restoring them -- if I dump a task
with aio ring originally mapped at address A, I want to restore one
back at exactly the same address A. Unfortunately, the io_setup() does
not allow for that -- it mmaps the ring at whatever place mm finds
appropriate (it calls do_mmap_pgoff() with zero address and without
the MAP_FIXED flag).

To make restore possible I'm going to mremap() the freshly created ring
into the address A (under which it was seen before dump). The problem is
that the ring's virtual address is passed back to the user-space as the
context ID and this ID is then used as search key by all the other io_foo()
calls. Reworking this ID to be just some integer doesn't seem to work, as
this value is already used by libaio as a pointer using which this library
accesses memory for aio meta-data.

So, to make restore work we need to make sure that

a) ring is mapped at desired virtual address
b) kioctx->user_id matches this value

Having said that, the patch makes mremap() on aio region update the
kioctx's user_id and mmap_base values.

Here appears the 2nd issue I mentioned in the beginning of this mail.
If (regardless of the C/R dances I do) someone creates an io context
with io_setup(), then mremap()-s the ring and then destroys the context,
the kill_ioctx() routine will call munmap() on wrong (old) address.
This will result in a) aio ring remaining in memory and b) some other
vma get unexpectedly unmapped.

What do you think?

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-12-13 17:49:50 -05:00
..
backing-dev.c Merge branch 'for-3.18/core' of git://git.kernel.dk/linux-block 2014-10-18 11:53:51 -07:00
balloon_compaction.c mm/balloon_compaction: fix deflation when compaction is disabled 2014-10-29 16:33:15 -07:00
bootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
cma.c mm: cma: Use %pa to print physical addresses 2014-10-27 13:00:55 +01:00
compaction.c mm, compaction: prevent infinite loop in compact_zone 2014-11-13 16:17:06 -08:00
debug-pagealloc.c
debug.c mm/debug.c: use pr_emerg() 2014-10-09 22:25:59 -04:00
dmapool.c mm/dmapool.c: fixed a brace coding style issue 2014-10-09 22:26:00 -04:00
early_ioremap.c mm: create generic early_ioremap() support 2014-04-07 16:36:15 -07:00
fadvise.c
failslab.c
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
filemap.c mm/filemap.c: remove trailing whitespace 2014-10-09 22:26:00 -04:00
fremap.c mm: mark remap_file_pages() syscall as deprecated 2014-06-06 16:08:17 -07:00
frontswap.c mm: frontswap: invalidate expired data on a dup-store failure 2014-12-02 17:32:07 -08:00
gup.c mm: introduce a general RCU get_user_pages_fast() 2014-10-09 22:26:00 -04:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c mm, thp: fix collapsing of hugepages on madvise 2014-10-29 16:33:14 -07:00
hugetlb_cgroup.c hugetlb_cgroup: use lockdep_assert_held rather than spin_is_locked 2014-08-29 16:28:16 -07:00
hugetlb.c mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMA 2014-10-09 22:25:57 -04:00
hwpoison-inject.c mm/hwpoison-inject.c: remove unnecessary null test before debugfs_remove_recursive 2014-08-06 18:01:19 -07:00
init-mm.c
internal.h mm/page_alloc: restrict max order of merging on isolated pageblock 2014-11-13 16:17:05 -08:00
interval_tree.c mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMA 2014-10-09 22:25:57 -04:00
iov_iter.c Fix thinko in iov_iter_single_seg_count 2014-11-13 13:28:55 -05:00
Kconfig mm/balloon_compaction: add vmstat counters and kpageflags bit 2014-10-09 22:26:01 -04:00
Kconfig.debug
kmemcheck.c mm/slab_common: move kmem_cache definition to internal header 2014-10-09 22:25:50 -04:00
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c mm: introduce kmemleak_update_trace() 2014-06-06 16:08:17 -07:00
ksm.c mm: ksm use pr_err instead of printk 2014-10-09 22:26:00 -04:00
list_lru.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
maccess.c
madvise.c mm: update the description for madvise_remove 2014-08-06 18:01:18 -07:00
Makefile Fixup for 3.18: use PATCHv2 of "mm: Support compiling out madvise and fadvise" 2014-10-12 09:21:57 -04:00
memblock.c mem-hotplug: let memblock skip the hotpluggable memory regions in __next_mem_range() 2014-09-10 15:42:12 -07:00
memcontrol.c mm: memcontrol: fix missed end-writeback page accounting 2014-10-29 16:33:15 -07:00
memory_hotplug.c mem-hotplug: reset node present pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
memory-failure.c cgroup: remove redundant check in cgroup_ino() 2014-09-19 09:16:23 -04:00
memory.c mm: fix swapoff hang after page migration and fork 2014-12-03 09:36:03 -08:00
mempolicy.c mm: mempolicy: skip inaccessible VMAs when setting MPOL_MF_LAZY 2014-10-09 22:26:02 -04:00
mempool.c mm/mempool.c: update the kmemleak stack trace for mempool allocations 2014-06-06 16:08:17 -07:00
migrate.c mm/balloon_compaction: redesign ballooned pages management 2014-10-09 22:26:01 -04:00
mincore.c mm + fs: prepare for non-page entries in page cache radix trees 2014-04-03 16:21:00 -07:00
mlock.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-10-13 15:44:12 +02:00
mm_init.c mm: bring back /sys/kernel/mm 2014-01-27 21:02:39 -08:00
mmap.c mm: fix anon_vma_clone() error treatment 2014-12-03 09:36:04 -08:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c kvm: Fix page ageing bugs 2014-09-24 14:07:58 +02:00
mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared 2014-10-14 02:18:28 +02:00
mremap.c aio: Make it possible to remap aio ring 2014-12-13 17:49:50 -05:00
msync.c msync: fix incorrect fstart calculation 2014-07-03 09:21:53 -07:00
nobootmem.c mem-hotplug: reset node managed pages when hot-adding a new pgdat 2014-11-13 16:17:06 -08:00
nommu.c percpu_counter: add @gfp to percpu_counter_init() 2014-09-08 09:51:29 +09:00
oom_kill.c OOM, PM: OOM killed task shouldn't escape PM suspend 2014-10-21 23:44:21 +02:00
page_alloc.c mm/debug-pagealloc: correct freepage accounting and order resetting 2014-11-13 16:17:06 -08:00
page_cgroup.c cgroup/kmemleak: add kmemleak_free() for cgroup deallocations. 2014-10-29 16:33:13 -07:00
page_io.c fix __swap_writepage() compile failure on old gcc versions 2014-06-14 19:30:48 -05:00
page_isolation.c mm/page_alloc: restrict max order of merging on isolated pageblock 2014-11-13 16:17:05 -08:00
page-writeback.c mm: memcontrol: fix missed end-writeback page accounting 2014-10-29 16:33:15 -07:00
pagewalk.c mm: use VM_BUG_ON_MM where possible 2014-10-09 22:25:58 -04:00
percpu-km.c percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated 2014-09-02 14:46:05 -04:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c percpu: fix how @gfp is interpreted by the percpu allocator 2014-10-08 12:01:52 -04:00
pgtable-generic.c mm: actually clear pmd_numa before invalidating 2014-08-29 16:28:15 -07:00
process_vm_access.c start adding the tag to iov_iter 2014-05-06 17:32:49 -04:00
quicklist.c
readahead.c mm/readahead.c: remove unused file_ra_state from count_history_pages 2014-08-06 18:01:15 -07:00
rmap.c mm: fix anon_vma_clone() error treatment 2014-12-03 09:36:04 -08:00
shmem.c shmem: support RENAME_WHITEOUT 2014-10-24 00:14:37 +02:00
slab_common.c mm/slab: fix unalignment problem on Malta with EVA due to slab merge 2014-11-13 16:17:05 -08:00
slab.c slab: fix nodeid bounds check for non-contiguous node IDs 2014-12-03 09:36:04 -08:00
slab.h mm/slab: use percpu allocator for cpu cache 2014-10-09 22:25:51 -04:00
slob.c mm/sl[ao]b: always track caller in kmalloc_(node_)track_caller() 2014-10-09 22:25:50 -04:00
slub.c mm/slab_common: commonize slab merge logic 2014-10-09 22:25:51 -04:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap_state.c mm: memcontrol: do not kill uncharge batching in free_pages_and_swap_cache 2014-10-09 22:25:59 -04:00
swap.c mm: memcontrol: do not kill uncharge batching in free_pages_and_swap_cache 2014-10-09 22:25:59 -04:00
swapfile.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
truncate.c mm: Fix comment before truncate_setsize() 2014-11-07 08:29:25 +11:00
util.c proc/maps: make vm_is_stack() logic namespace-friendly 2014-10-09 22:25:50 -04:00
vmacache.c mm,vmacache: optimize overflow system-wide flushing 2014-06-04 16:53:57 -07:00
vmalloc.c mm/vmalloc.c: use seq_open_private() instead of seq_open() 2014-10-09 22:25:56 -04:00
vmpressure.c mm/vmpressure.c: fix race in vmpressure_work_fn() 2014-12-02 17:32:07 -08:00
vmscan.c mm: memcontrol: fix transparent huge page allocations under pressure 2014-10-09 22:25:59 -04:00
vmstat.c vmstat: on-demand vmstat workers V8 2014-10-09 22:26:02 -04:00
workingset.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
zbud.c zbud: avoid accessing last unused freelist 2014-10-09 22:26:03 -04:00
zpool.c mm/zpool: use prefixed module loading 2014-08-29 16:28:16 -07:00
zsmalloc.c zsmalloc: simplify init_zspage free obj linking 2014-10-09 22:26:03 -04:00
zswap.c mm/zswap.c: add __init to zswap_entry_cache_destroy() 2014-08-08 15:57:18 -07:00