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12e967fd8e
linux/mm
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Michal Hocko 12e967fd8e mm: do not allow MADV_PAGEOUT for CoW pages 
Jann has brought up a very interesting point [1].  While shared pages
are excluded from MADV_PAGEOUT normally, CoW pages can be easily
reclaimed that way.  This can lead to all sorts of hard to debug
problems.  E.g.  performance problems outlined by Daniel [2].

There are runtime environments where there is a substantial memory
shared among security domains via CoW memory and a easy to reclaim way
of that memory, which MADV_{COLD,PAGEOUT} offers, can lead to either
performance degradation in for the parent process which might be more
privileged or even open side channel attacks.

The feasibility of the latter is not really clear to me TBH but there is
no real reason for exposure at this stage.  It seems there is no real
use case to depend on reclaiming CoW memory via madvise at this stage so
it is much easier to simply disallow it and this is what this patch
does.  Put it simply MADV_{PAGEOUT,COLD} can operate only on the
exclusively owned memory which is a straightforward semantic.

[1] http://lkml.kernel.org/r/CAG48ez0G3JkMq61gUmyQAaCq=_TwHbi1XKzWRooxZkv08PQKuw@mail.gmail.com
[2] http://lkml.kernel.org/r/CAKOZueua_v8jHCpmEtTB6f3i9e2YnmX4mqdYVWhV4E=Z-n+zRQ@mail.gmail.com

Fixes: 9c276cc65a ("mm: introduce MADV_COLD")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Daniel Colascione <dancol@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200312082248.GS23944@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-03-21 18:56:06 -07:00
..
kasan RISC-V Patches for the 5.6 Merge Window, Part 1 2020-01-31 11:23:29 -08:00
backing-dev.c memcg: fix a crash in wb_workfn when a device disappears 2020-01-31 10:30:36 -08:00
balloon_compaction.c
cleancache.c
cma_debug.c mm/cma_debug.c: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops 2019-12-01 12:59:09 -08:00
cma.c mm/cma.c: switch to bitmap_zalloc() for cma bitmap allocation 2019-12-01 12:59:09 -08:00
cma.h
compaction.c mm, compaction: fix wrong pfn handling in __reset_isolation_pfn() 2019-10-14 15:04:01 -07:00
debug_page_ref.c
debug.c mm/hotplug: silence a lockdep splat with printk() 2020-01-31 10:30:39 -08:00
dmapool.c
early_ioremap.c mm/early_ioremap.c: use %pa to print resource_size_t variables 2020-01-31 10:30:38 -08:00
fadvise.c
failslab.c
filemap.c mm/filemap.c: clean up filemap_write_and_wait() 2020-01-31 10:30:37 -08:00
frame_vector.c mm: untag user pointers in get_vaddr_frames 2019-09-25 17:51:41 -07:00
frontswap.c
gup_benchmark.c mm/gup_benchmark: use proper FOLL_WRITE flags instead of hard-coding "1" 2020-01-31 10:30:38 -08:00
gup.c asm-generic/tlb: rename HAVE_RCU_TABLE_FREE 2020-02-04 03:05:26 +00:00
highmem.c mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions 2019-12-10 10:12:55 +01:00
hmm.c mm: pagewalk: add 'depth' parameter to pte_hole 2020-02-04 03:05:25 +00:00
huge_memory.c mm: fix possible PMD dirty bit lost in set_pmd_migration_entry() 2020-03-06 07:06:09 -06:00
hugetlb_cgroup.c mm: hugetlb controller for cgroups v2 2019-12-16 12:41:40 -08:00
hugetlb.c mm/hugetlb: defer freeing of huge pages if in non-task context 2020-01-04 13:55:09 -08:00
hwpoison-inject.c mm/hwpoison-inject: use DEFINE_DEBUGFS_ATTRIBUTE to define debugfs fops 2019-12-01 12:59:09 -08:00
init-mm.c mm/init-mm.c: include <linux/mman.h> for vm_committed_as_batch 2019-10-19 06:32:32 -04:00
internal.h mm, pcpu: make zone pcp updates and reset internal to the mm 2019-12-01 12:59:06 -08:00
interval_tree.c
Kconfig mm/Kconfig: fix trivial help text punctuation 2019-12-01 12:59:10 -08:00
Kconfig.debug mm: add generic ptdump 2020-02-04 03:05:25 +00:00
khugepaged.c mm/thp: flush file for !is_shmem PageDirty() case in collapse_file() 2019-12-01 12:59:09 -08:00
kmemleak-test.c
kmemleak.c mm/kmemleak: turn kmemleak_lock and object->lock to raw_spinlock_t 2020-01-31 10:30:36 -08:00
ksm.c * PPC secure guest support 2019-12-04 11:08:30 -08:00
list_lru.c
maccess.c uaccess: Add strict non-pagefault kernel-space read function 2019-11-02 12:39:12 -07:00
madvise.c mm: do not allow MADV_PAGEOUT for CoW pages 2020-03-21 18:56:06 -07:00
Makefile mm: add generic ptdump 2020-02-04 03:05:25 +00:00
mapping_dirty_helpers.c mm: Add write-protect and clean utilities for address space ranges 2019-11-06 13:03:36 +01:00
memblock.c memblock: Use __func__ in remaining memblock_dbg() call sites 2020-01-31 10:30:38 -08:00
memcontrol.c mm, memcg: throttle allocators based on ancestral memory.high 2020-03-21 18:56:06 -07:00
memfd.c mm: page cache: store only head pages in i_pages 2019-09-24 15:54:08 -07:00
memory_hotplug.c mm, hotplug: fix page online with DEBUG_PAGEALLOC compiled but not enabled 2020-03-06 07:06:09 -06:00
memory-failure.c mm/memory-failure.c: use page_shift() in add_to_kill() 2019-12-01 12:59:04 -08:00
memory.c mm: avoid data corruption on CoW fault into PFN-mapped VMA 2020-03-06 07:06:09 -06:00
mempolicy.c mm/mempolicy.c: fix out of bounds write in mpol_parse_str() 2020-01-31 10:30:36 -08:00
mempool.c
memremap.c mm/memory_hotplug: poison memmap in remove_pfn_range_from_zone() 2020-02-04 03:05:23 +00:00
memtest.c
migrate.c mm: pagewalk: add 'depth' parameter to pte_hole 2020-02-04 03:05:25 +00:00
mincore.c mm: pagewalk: add 'depth' parameter to pte_hole 2020-02-04 03:05:25 +00:00
mlock.c mm: untag user pointers passed to memory syscalls 2019-09-25 17:51:41 -07:00
mm_init.c
mmap.c mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-20 10:03:14 +00:00
mmu_context.c
mmu_gather.c asm-generic/tlb: provide MMU_GATHER_TABLE_FREE 2020-02-04 03:05:26 +00:00
mmu_notifier.c mm/mmu_notifiers: Use 'interval_sub' as the variable for mmu_interval_notifier 2020-01-14 11:54:47 -04:00
mmzone.c
mprotect.c mm, numa: fix bad pmd by atomically check for pmd_trans_huge when marking page tables prot_numa 2020-03-06 07:06:09 -06:00
mremap.c mm: Avoid creating virtual address aliases in brk()/mmap()/mremap() 2020-02-20 10:03:14 +00:00
msync.c mm: untag user pointers passed to memory syscalls 2019-09-25 17:51:41 -07:00
nommu.c mm/mmap.c: rb_parent is not necessary in __vma_link_list() 2019-12-01 06:29:19 -08:00
oom_kill.c mm, oom: dump stack of victim when reaping failed 2020-01-31 10:30:38 -08:00
page_alloc.c mm/memmap_init: update variable name in memmap_init_zone 2020-02-04 03:05:23 +00:00
page_counter.c
page_ext.c mm, page_owner: fix off-by-one error in __set_page_owner_handle() 2019-10-14 15:04:00 -07:00
page_idle.c
page_io.c fs: Enable bmap() function to properly return errors 2020-02-03 08:05:37 -05:00
page_isolation.c mm/page_isolation: fix potential warning from user 2020-01-31 10:30:39 -08:00
page_owner.c mm/page_owner: don't access uninitialized memmaps when reading /proc/pagetypeinfo 2019-10-19 06:32:31 -04:00
page_poison.c
page_vma_mapped.c mm/page_vma_mapped.c: explicitly compare pfn for normal, hugetlbfs and THP page 2020-01-31 10:30:38 -08:00
page-writeback.c mm/page-writeback.c: improve arithmetic divisions 2020-01-13 18:19:02 -08:00
pagewalk.c x86: mm: avoid allocating struct mm_struct on the stack 2020-02-04 03:05:25 +00:00
percpu-internal.h
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c bitmap: genericize percpu bitmap region iterators 2020-01-20 16:40:56 +01:00
pgtable-generic.c asm-generic/mm: stub out p{4,u}d_clear_bad() if __PAGETABLE_P{4,U}D_FOLDED 2019-12-01 06:29:19 -08:00
process_vm_access.c mm, tree-wide: rename put_user_page*() to unpin_user_page*() 2020-01-31 10:30:38 -08:00
ptdump.c x86: mm: avoid allocating struct mm_struct on the stack 2020-02-04 03:05:25 +00:00
readahead.c
rmap.c mm, thp: do not queue fully unmapped pages for deferred split 2019-12-01 12:59:09 -08:00
rodata_test.c
shmem.c tmpfs: deny and force are not huge mount options 2020-02-18 15:07:30 -05:00
shuffle.c mm: fix -Wmissing-prototypes warnings 2019-10-07 15:47:19 -07:00
shuffle.h
slab_common.c proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
slab.c mm, debug_pagealloc: don't rely on static keys too early 2020-01-13 18:19:02 -08:00
slab.h mm: clean up and clarify lruvec lookup procedure 2019-12-01 12:59:06 -08:00
slob.c mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two) 2019-10-07 15:47:20 -07:00
slub.c mm: slub: be more careful about the double cmpxchg of freelist 2020-03-18 09:40:32 -07:00
sparse-vmemmap.c
sparse.c mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case 2020-03-21 18:56:06 -07:00
swap_cgroup.c
swap_slots.c
swap_state.c mm: page cache: store only head pages in i_pages 2019-09-24 15:54:08 -07:00
swap.c mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages 2020-01-31 10:30:37 -08:00
swapfile.c mm/swapfile.c: fix a comment in sys_swapon() 2020-02-21 11:22:15 -08:00
truncate.c mm/thp: allow dropping THP from page cache 2019-10-19 06:32:33 -04:00
usercopy.c
userfaultfd.c mm: fix typos in comments when calling __SetPageUptodate() 2019-12-01 12:59:10 -08:00
util.c mm/mmap.c: rb_parent is not necessary in __vma_link_list() 2019-12-01 06:29:19 -08:00
vmacache.c
vmalloc.c Linux 5.5-rc7 2020-01-20 08:05:16 +01:00
vmpressure.c mm/vmpressure.c: fix a signedness bug in vmpressure_register_event() 2019-10-07 15:47:19 -07:00
vmscan.c mm/vmscan.c: don't round up scan size for online memory cgroup 2020-02-21 11:22:15 -08:00
vmstat.c mm/memcontrol: use vmstat names for printing statistics 2019-12-04 19:44:11 -08:00
workingset.c mm: vmscan: detect file thrashing at the reclaim root 2019-12-01 12:59:07 -08:00
z3fold.c mm/z3fold.c: do not include rwlock.h directly 2020-03-06 07:06:09 -06:00
zbud.c
zpool.c zpool: add malloc_support_movable to zpool_driver 2019-09-24 15:54:12 -07:00
zsmalloc.c mm/zsmalloc.c: fix the migrated zspage statistics. 2020-01-04 13:55:09 -08:00
zswap.c zswap: potential NULL dereference on error in init_zswap() 2020-01-31 10:30:39 -08:00