kernel_optimize_test/mm
Lars Persson d2b2c6dd22 mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate
Our MIPS 1004Kc SoCs were seeing random userspace crashes with SIGILL
and SIGSEGV that could not be traced back to a userspace code bug.  They
had all the magic signs of an I/D cache coherency issue.

Now recently we noticed that the /proc/sys/vm/compact_memory interface
was quite efficient at provoking this class of userspace crashes.

Studying the code in mm/migrate.c there is a distinction made between
migrating a page that is mapped at the instant of migration and one that
is not mapped.  Our problem turned out to be the non-mapped pages.

For the non-mapped page the code performs a copy of the page content and
all relevant meta-data of the page without doing the required D-cache
maintenance.  This leaves dirty data in the D-cache of the CPU and on
the 1004K cores this data is not visible to the I-cache.  A subsequent
page-fault that triggers a mapping of the page will happily serve the
process with potentially stale code.

What about ARM then, this bug should have seen greater exposure? Well
ARM became immune to this flaw back in 2010, see commit c01778001a
("ARM: 6379/1: Assume new page cache pages have dirty D-cache").

My proposed fix moves the D-cache maintenance inside move_to_new_page to
make it common for both cases.

Link: http://lkml.kernel.org/r/20190315083502.11849-1-larper@axis.com
Fixes: 97ee052461 ("flush cache before installing new page at migraton")
Signed-off-by: Lars Persson <larper@axis.com>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-29 10:01:37 -07:00
..
kasan kasan: fix variable 'tag' set but not used warning 2019-03-29 10:01:36 -07:00
backing-dev.c
balloon_compaction.c
cleancache.c
cma_debug.c
cma.c memblock: emphasize that memblock_alloc_range() returns a physical address 2019-03-12 10:04:01 -07:00
cma.h
compaction.c
debug_page_ref.c
debug.c mm/debug.c: fix __dump_page when mapping->host is not set 2019-03-29 10:01:37 -07:00
dmapool.c
early_ioremap.c
fadvise.c
failslab.c
filemap.c filemap: add a comment about FAULT_FLAG_RETRY_NOWAIT behavior 2019-03-15 11:26:07 -07:00
frame_vector.c
frontswap.c
gup_benchmark.c
gup.c
highmem.c
hmm.c mm/hmm: convert to use vm_fault_t 2019-03-12 10:04:00 -07:00
huge_memory.c
hugetlb_cgroup.c
hugetlb.c
hwpoison-inject.c
init-mm.c
internal.h
interval_tree.c
Kconfig
Kconfig.debug
khugepaged.c
kmemleak-test.c
kmemleak.c
ksm.c
list_lru.c
maccess.c
madvise.c
Makefile
memblock.c mm: memblock: update comments and kernel-doc 2019-03-12 10:04:02 -07:00
memcontrol.c
memfd.c
memory_hotplug.c mm/memory_hotplug.c: fix notification in offline error path 2019-03-29 10:01:37 -07:00
memory-failure.c
memory.c mm/memory.c: fix modifying of page protection by insert_pfn() 2019-03-29 10:01:37 -07:00
mempolicy.c mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified 2019-03-29 10:01:37 -07:00
mempool.c
memtest.c
migrate.c mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate 2019-03-29 10:01:37 -07:00
mincore.c
mlock.c
mm_init.c
mmap.c
mmu_context.c
mmu_gather.c
mmu_notifier.c
mmzone.c
mprotect.c
mremap.c
msync.c
nommu.c
oom_kill.c
page_alloc.c mm/hotplug: fix offline undo_isolate_page_range() 2019-03-29 10:01:37 -07:00
page_counter.c
page_ext.c memblock: drop memblock_alloc_*_nopanic() variants 2019-03-12 10:04:02 -07:00
page_idle.c
page_io.c
page_isolation.c mm/page_isolation.c: fix a wrong flag in set_migratetype_isolate() 2019-03-29 10:01:37 -07:00
page_owner.c
page_poison.c
page_vma_mapped.c
page-writeback.c
pagewalk.c
percpu-internal.h
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c memblock: drop memblock_alloc_*_nopanic() variants 2019-03-12 10:04:02 -07:00
pgtable-generic.c
process_vm_access.c
quicklist.c
readahead.c
rmap.c
rodata_test.c
shmem.c
slab_common.c mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
slab.c mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
slab.h mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
slob.c
slub.c mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
sparse-vmemmap.c
sparse.c mm/hotplug: fix offline undo_isolate_page_range() 2019-03-29 10:01:37 -07:00
swap_cgroup.c
swap_slots.c
swap_state.c
swap.c
swapfile.c
truncate.c
usercopy.c
userfaultfd.c
util.c
vmacache.c
vmalloc.c
vmpressure.c
vmscan.c
vmstat.c
workingset.c
z3fold.c
zbud.c
zpool.c
zsmalloc.c
zswap.c