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anfei zhou 3a9353f232 mm: flush dcache before writing into page to avoid alias 
commit 931e80e4b3 upstream.

The cache alias problem will happen if the changes of user shared mapping
is not flushed before copying, then user and kernel mapping may be mapped
into two different cache line, it is impossible to guarantee the coherence
after iov_iter_copy_from_user_atomic.  So the right steps should be:

	flush_dcache_page(page);
	kmap_atomic(page);
	write to page;
	kunmap_atomic(page);
	flush_dcache_page(page);

More precisely, we might create two new APIs flush_dcache_user_page and
flush_dcache_kern_page to replace the two flush_dcache_page accordingly.

Here is a snippet tested on omap2430 with VIPT cache, and I think it is
not ARM-specific:

	int val = 0x11111111;
	fd = open("abc", O_RDWR);
	addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	*(addr+0) = 0x44444444;
	tmp = *(addr+0);
	*(addr+1) = 0x77777777;
	write(fd, &val, sizeof(int));
	close(fd);

The results are not always 0x11111111 0x77777777 at the beginning as expected.  Sometimes we see 0x44444444 0x77777777.

Signed-off-by: Anfei <anfei.zhou@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-02-09 04:50:59 -08:00
..
allocpercpu.c percpu: use dynamic percpu allocator as the default percpu allocator 2009-06-24 15:13:35 +09:00
backing-dev.c Thaw refrigerated bdi flusher threads before invoking kthread_stop on them 2009-11-12 13:08:11 +01:00
bootmem.c kmemleak: Do not report alloc_bootmem blocks as leaks 2009-08-27 14:29:17 +01:00
bounce.c block: remove some includings of blktrace_api.h 2009-06-16 11:19:36 +02:00
debug-pagealloc.c generic debug pagealloc 2009-04-01 08:59:13 -07:00
dmapool.c dmapools: protect page_list walk in show_pools() 2009-06-30 18:56:00 -07:00
fadvise.c readahead: move max_sane_readahead() calls into force_page_cache_readahead() 2009-06-16 19:47:28 -07:00
failslab.c kmemtrace, mm: fix slab.h dependency problem in mm/failslab.c 2009-04-03 12:23:01 +02:00
filemap.c mm: flush dcache before writing into page to avoid alias 2010-02-09 04:50:59 -08:00
filemap_xip.c const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
fremap.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
highmem.c highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE 2009-11-10 04:15:47 +01:00
hugetlb.c const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
hwpoison-inject.c HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs 2009-09-16 11:50:17 +02:00
init-mm.c mm: consolidate init_mm definition 2009-06-16 19:47:28 -07:00
internal.h ksm: fix mlockfreed to munlocked 2010-01-06 15:05:22 -08:00
Kconfig NOMMU: Optimise away the {dac_,}mmap_min_addr tests 2010-01-06 15:04:30 -08:00
Kconfig.debug trivial: improve help text for mm debug config options 2009-09-21 15:14:57 +02:00
kmemcheck.c kmemcheck: add hooks for the page allocator 2009-06-15 15:48:33 +02:00
kmemleak-test.c percpu: clean up percpu variable definitions 2009-06-24 15:13:48 +09:00
kmemleak.c kmemleak: Check for NULL pointer returned by create_object() 2009-10-09 13:28:47 -07:00
ksm.c ksm: fix mlockfreed to munlocked 2010-01-06 15:05:22 -08:00
maccess.c [S390] maccess: add weak attribute to probe_kernel_write 2009-06-12 10:27:37 +02:00
madvise.c Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2009-09-24 07:53:22 -07:00
Makefile procfs: disable per-task stack usage on NOMMU 2009-09-24 17:11:24 -07:00
memcontrol.c memcg: ensure list is empty at rmdir 2010-01-22 15:18:01 -08:00
memory-failure.c hwpoison: fix oops on ksm pages 2009-10-29 07:39:24 -07:00
memory.c mm: sigbus instead of abusing oom 2009-12-18 14:05:51 -08:00
memory_hotplug.c mm: allow memory hotplug and hibernation in the same kernel 2009-11-17 17:40:33 -08:00
mempolicy.c do_mbind(): fix memory leak 2009-10-29 07:39:29 -07:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c memcg: fix wrong pointer initialization at page migration when memcg is disabled. 2009-11-12 07:25:56 -08:00
mincore.c mm: hugetlb: fix hugepage memory leak in mincore() 2009-12-18 14:04:29 -08:00
mlock.c ksm: fix mlockfreed to munlocked 2010-01-06 15:05:22 -08:00
mm_init.c
mmap.c untangle the do_mremap() mess 2010-01-18 10:19:11 -08:00
mmu_context.c mm: reduce atomic use on use_mm fast path 2009-09-22 07:17:42 -07:00
mmu_notifier.c ksm: add mmu_notifier set_pte_at_notify() 2009-09-22 07:17:31 -07:00
mmzone.c [ARM] Double check memmap is actually valid with a memmap has unexpected holes V2 2009-05-18 11:22:24 +01:00
mprotect.c perf: Do the big rename: Performance Counters -> Performance Events 2009-09-21 14:28:04 +02:00
mremap.c untangle the do_mremap() mess 2010-01-18 10:19:11 -08:00
msync.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
nommu.c NOMMU: Don't pass NULL pointers to fput() in do_mmap_pgoff() 2009-10-31 12:11:37 -07:00
oom_kill.c memcg: avoid oom-killing innocent task in case of use_hierarchy 2010-01-06 15:04:37 -08:00
page-writeback.c writeback: account IO throttling wait as iowait 2009-10-09 12:40:42 +02:00
page_alloc.c mm: fix migratetype bug which slowed swapping 2010-02-09 04:50:49 -08:00
page_cgroup.c memory hotplug: alloc page from other node in memory online 2009-09-22 07:17:26 -07:00
page_io.c mm: remove file argument from swap_readpage() 2009-06-16 19:47:44 -07:00
page_isolation.c memory hotplug: fix page_zone() calculation in test_pages_isolated() 2008-11-06 15:41:19 -08:00
pagewalk.c mm: hugetlb: fix hugepage memory leak in walk_page_range() 2009-12-18 14:04:30 -08:00
percpu.c percpu: restructure pcpu_extend_area_map() to fix bugs and improve readability 2009-11-13 00:55:35 +09:00
prio_tree.c
quicklist.c cpumask: use new-style cpumask ops in mm/quicklist. 2009-09-24 09:34:52 +09:30
readahead.c readahead: introduce context readahead algorithm 2009-06-16 19:47:30 -07:00
rmap.c mm/rmap.c: fix comment 2009-10-01 16:11:12 -07:00
shmem.c const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
shmem_acl.c shmfs: use 'check_acl' instead of 'permission' 2009-09-08 11:08:46 -07:00
slab.c mm: replace various uses of num_physpages by totalram_pages 2009-09-22 07:17:38 -07:00
slob.c slab: remove duplicate kmem_cache_init_late() declarations 2009-08-06 11:36:25 +03:00
slub.c mm: kmem_cache_create(): make it easier to catch NULL cache names 2009-09-22 07:17:33 -07:00
sparse-vmemmap.c memory hotplug: alloc page from other node in memory online 2009-09-22 07:17:26 -07:00
sparse.c memory hotplug: alloc page from other node in memory online 2009-09-22 07:17:26 -07:00
swap.c mm: replace various uses of num_physpages by totalram_pages 2009-09-22 07:17:38 -07:00
swap_state.c mm: add_to_swap_cache() does not return -EEXIST 2009-09-22 07:17:35 -07:00
swapfile.c mm: remove incorrect swap_count() from try_to_unuse() 2009-11-02 09:44:41 -08:00
thrash.c mm: pass mm to grab_swap_token 2009-06-23 12:50:05 -07:00
truncate.c vfs: Fix vmtruncate() regression 2010-01-22 15:18:41 -08:00
util.c untangle the do_mremap() mess 2010-01-18 10:19:11 -08:00
vmalloc.c mm: purge fragmented percpu vmap blocks 2010-02-09 04:50:58 -08:00
vmscan.c vmscan: do not evict inactive pages when skipping an active list scan 2010-01-06 15:05:21 -08:00
vmstat.c mm: vmstat: add isolate pages 2009-09-22 07:17:29 -07:00