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931e80e4b3
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anfei zhou 931e80e4b3 mm: flush dcache before writing into page to avoid alias 
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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-02-02 18:11:21 -08:00
..
backing-dev.c flusher: Fix PF_FROZEN race 2009-12-03 13:49:43 +01:00
bootmem.c mm/bootmem.c: properly __init-annotate helper functions 2009-12-15 08:53:20 -08:00
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_xip.c const: mark struct vm_struct_operations 2009-09-27 11:39:25 -07:00
filemap.c mm: flush dcache before writing into page to avoid alias 2010-02-02 18:11:21 -08:00
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 mm: hugetlb: fix clear_huge_page() 2010-01-11 09:34:06 -08:00
hwpoison-inject.c HWPOISON: Don't do early filtering if filter is disabled 2009-12-16 12:20:01 +01:00
init-mm.c mm: consolidate init_mm definition 2009-06-16 19:47:28 -07:00
internal.h HWPOISON: add an interface to switch off/on all the page filters 2009-12-16 12:19:59 +01:00
Kconfig HWPOISON: Add PROC_FS dependency to hwpoison injector v2 2009-12-21 19:56:42 +01:00
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 Merge branch 'kmemleak' of git://linux-arm.org/linux-2.6 2009-12-17 16:00:19 -08:00
ksm.c ksm: remove unswappable max_kernel_pages 2009-12-15 08:53:20 -08:00
maccess.c maccess,probe_kernel: Allow arch specific override probe_kernel_(read|write) 2010-01-07 11:58:36 -06:00
madvise.c HWPOISON: Add a madvise() injector for soft page offlining 2009-12-16 12:20:00 +01:00
Makefile make generic_acl slightly more generic 2009-12-16 12:16:49 -05:00
memcontrol.c memcg: ensure list is empty at rmdir 2010-01-16 12:15:39 -08:00
memory_hotplug.c mm: fix section mismatch in memory_hotplug.c 2009-12-15 08:53:20 -08:00
memory-failure.c HWPOISON: Add PROC_FS dependency to hwpoison injector v2 2009-12-21 19:56:42 +01:00
memory.c Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6 2009-12-16 12:36:49 -08:00
mempolicy.c ksm: memory hotremove migration only 2009-12-15 08:53:20 -08:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c mm: remove unevictable_migrate_page function 2009-12-15 08:53:23 -08:00
mincore.c mm: hugetlb: fix hugepage memory leak in mincore() 2009-12-15 08:53:24 -08:00
mlock.c mlock: replace stale comments in munlock_vma_page() 2009-12-15 08:53:23 -08:00
mm_init.c mm: mminit_loglevel cannot be __meminitdata anymore 2008-08-20 15:40:30 -07:00
mmap.c mm: move sys_mmap_pgoff from util.c 2009-12-30 12:23:27 -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 Take arch_mmap_check() into get_unmapped_area() 2009-12-11 06:44:58 -05:00
msync.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
nommu.c nommu: fix shared mmap after truncate shrinkage problems 2010-01-16 12:15:40 -08:00
oom_kill.c memcg: avoid oom-killing innocent task in case of use_hierarchy 2009-12-16 07:20:07 -08:00
page_alloc.c mm: fix migratetype bug which slowed swapping 2010-01-29 10:28:09 -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 swap: rework map_swap_page() again 2009-12-15 08:53:16 -08:00
page_isolation.c memory hotplug: fix page_zone() calculation in test_pages_isolated() 2008-11-06 15:41:19 -08:00
page-writeback.c writeback: remove unused nonblocking and congestion checks 2009-12-03 13:54:25 +01:00
pagewalk.c mm hugetlb: add hugepage support to pagemap 2009-12-15 08:53:24 -08:00
percpu.c percpu: avoid calling __pcpu_ptr_to_addr(NULL) 2010-01-11 09:34:04 -08:00
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: add blk_run_backing_dev 2009-12-17 15:45:32 -08:00
rmap.c memcg: make memcg's file mapped consistent with global VM 2009-12-16 07:20:07 -08:00
shmem.c Fix breakage in shmem.c 2009-12-16 19:48:48 -05:00
slab.c SLAB: Fix lockdep annotation breakage 2009-12-28 20:57:27 +02:00
slob.c slab: remove duplicate kmem_cache_init_late() declarations 2009-08-06 11:36:25 +03:00
slub.c Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-14 10:13:22 -08:00
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_state.c mm: add_to_swap_cache() does not return -EEXIST 2009-09-22 07:17:35 -07:00
swap.c mm: replace various uses of num_physpages by totalram_pages 2009-09-22 07:17:38 -07:00
swapfile.c ksm: let shared pages be swappable 2009-12-15 08:53:19 -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 2010-01-13 16:09:33 -08:00
util.c nommu: don't need get_unmapped_area() for NOMMU 2010-01-16 12:15:40 -08:00
vmalloc.c mm: purge fragmented percpu vmap blocks 2010-02-02 12:50:47 -08:00
vmscan.c vmscan: kswapd: don't retry balance_pgdat() if all zones are unreclaimable 2010-01-16 12:15:39 -08:00
vmstat.c vmscan: stop kswapd waiting on congestion when the min watermark is not being met 2009-12-15 08:53:16 -08:00