linux_dsm_epyc7002/mm
Linus Torvalds 574823bfab Change mincore() to count "mapped" pages rather than "cached" pages
The semantics of what "in core" means for the mincore() system call are
somewhat unclear, but Linux has always (since 2.3.52, which is when
mincore() was initially done) treated it as "page is available in page
cache" rather than "page is mapped in the mapping".

The problem with that traditional semantic is that it exposes a lot of
system cache state that it really probably shouldn't, and that users
shouldn't really even care about.

So let's try to avoid that information leak by simply changing the
semantics to be that mincore() counts actual mapped pages, not pages
that might be cheaply mapped if they were faulted (note the "might be"
part of the old semantics: being in the cache doesn't actually guarantee
that you can access them without IO anyway, since things like network
filesystems may have to revalidate the cache before use).

In many ways the old semantics were somewhat insane even aside from the
information leak issue.  From the very beginning (and that beginning is
a long time ago: 2.3.52 was released in March 2000, I think), the code
had a comment saying

  Later we can get more picky about what "in core" means precisely.

and this is that "later".  Admittedly it is much later than is really
comfortable.

NOTE! This is a real semantic change, and it is for example known to
change the output of "fincore", since that program literally does a
mmmap without populating it, and then doing "mincore()" on that mapping
that doesn't actually have any pages in it.

I'm hoping that nobody actually has any workflow that cares, and the
info leak is real.

We may have to do something different if it turns out that people have
valid reasons to want the old semantics, and if we can limit the
information leak sanely.

Cc: Kevin Easton <kevin@guarana.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Masatake YAMATO <yamato@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-06 13:43:02 -08:00
..
kasan mm: treewide: remove unused address argument from pte_alloc functions 2019-01-04 13:13:47 -08:00
backing-dev.c
balloon_compaction.c
cleancache.c
cma_debug.c
cma.c kasan, mm, arm64: tag non slab memory allocated via pagealloc 2018-12-28 12:11:44 -08:00
cma.h
compaction.c mm: move zone watermark accesses behind an accessor 2018-12-28 12:11:48 -08:00
debug_page_ref.c
debug.c mm/debug.c: make "migrate_reason_names[]" const char * 2018-12-28 12:11:48 -08:00
dmapool.c
early_ioremap.c
fadvise.c
failslab.c
filemap.c mm/: remove caller signal_pending branch predictions 2019-01-04 13:13:48 -08:00
frame_vector.c
frontswap.c
gup_benchmark.c
gup.c Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
highmem.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
hmm.c mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm 2018-12-28 12:11:52 -08:00
huge_memory.c mm: treewide: remove unused address argument from pte_alloc functions 2019-01-04 13:13:47 -08:00
hugetlb_cgroup.c
hugetlb.c mm/: remove caller signal_pending branch predictions 2019-01-04 13:13:48 -08:00
hwpoison-inject.c
init-mm.c
internal.h mm: use alloc_flags to record if kswapd can wake 2018-12-28 12:11:48 -08:00
interval_tree.c
Kconfig ksm: replace jhash2 with xxhash 2018-12-28 12:11:46 -08:00
Kconfig.debug
khugepaged.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
kmemleak-test.c
kmemleak.c kmemleak: add config to select auto scan 2018-12-28 12:11:51 -08:00
ksm.c ksm: react on changing "sleep_millisecs" parameter faster 2018-12-28 12:11:51 -08:00
list_lru.c
maccess.c
madvise.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
Makefile
memblock.c mm/memblock.c: skip kmemleak for kasan_init() 2018-12-28 12:11:49 -08:00
memcontrol.c memcg, oom: notify on oom killer invocation from the charge path 2018-12-28 12:11:52 -08:00
memfd.c
memory_hotplug.c mm, memory_hotplug: deobfuscate migration part of offlining 2018-12-28 12:11:50 -08:00
memory-failure.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
memory.c mm: treewide: remove unused address argument from pte_alloc functions 2019-01-04 13:13:47 -08:00
mempolicy.c Revert "mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask" 2018-12-08 10:26:20 -08:00
mempool.c
memtest.c
migrate.c mm: treewide: remove unused address argument from pte_alloc functions 2019-01-04 13:13:47 -08:00
mincore.c Change mincore() to count "mapped" pages rather than "cached" pages 2019-01-06 13:43:02 -08:00
mlock.c
mm_init.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
mmap.c mm/mmap.c: remove verify_mm_writelocked() 2018-12-28 12:11:47 -08:00
mmu_context.c
mmu_gather.c
mmu_notifier.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
mmzone.c
mprotect.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
mremap.c mm: speed up mremap by 20x on large regions 2019-01-04 13:13:48 -08:00
msync.c
nommu.c
oom_kill.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
page_alloc.c mm/page_alloc.c: allow error injection 2018-12-28 12:11:51 -08:00
page_counter.c
page_ext.c
page_idle.c
page_io.c mm/page_io.c: fix polled swap page in 2019-01-04 13:13:48 -08:00
page_isolation.c mm: only report isolation failures when offlining memory 2018-12-28 12:11:46 -08:00
page_owner.c mm/page_owner: clamp read count to PAGE_SIZE 2018-12-28 12:11:46 -08:00
page_poison.c
page_vma_mapped.c
page-writeback.c mm/page-writeback.c: don't break integrity writeback on ->writepage() error 2018-12-28 12:11:49 -08:00
pagewalk.c
percpu-internal.h
percpu-km.c percpu: convert spin_lock_irq to spin_lock_irqsave. 2018-12-18 09:04:08 -08:00
percpu-stats.c
percpu-vm.c
percpu.c
pgtable-generic.c
process_vm_access.c
quicklist.c
readahead.c mm/readahead.c: simplify get_next_ra_size() 2018-12-28 12:11:46 -08:00
rmap.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
rodata_test.c
shmem.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
slab_common.c A fairly normal cycle for documentation stuff. We have a new 2018-12-29 11:21:49 -08:00
slab.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
slab.h kasan, mm: change hooks signatures 2018-12-28 12:11:43 -08:00
slob.c
slub.c mm/slub.c: record final state of slub action in deactivate_slab() 2018-12-28 12:11:46 -08:00
sparse-vmemmap.c
sparse.c mm, sparse: pass nid instead of pgdat to sparse_add_one_section() 2018-12-28 12:11:49 -08:00
swap_cgroup.c
swap_slots.c
swap_state.c
swap.c fs: don't open code lru_to_page() 2019-01-04 13:13:48 -08:00
swapfile.c mm, swap: fix swapoff with KSM pages 2018-12-28 12:11:52 -08:00
truncate.c
usercopy.c
userfaultfd.c mm: treewide: remove unused address argument from pte_alloc functions 2019-01-04 13:13:47 -08:00
util.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
vmacache.c
vmalloc.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
vmpressure.c
vmscan.c mm: put_and_wait_on_page_locked() while page is migrated 2018-12-28 12:11:48 -08:00
vmstat.c mm: convert zone->managed_pages to atomic variable 2018-12-28 12:11:47 -08:00
workingset.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
z3fold.c
zbud.c
zpool.c
zsmalloc.c
zswap.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00