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
mm: treewide: remove unused address argument from pte_alloc functions
2019-01-04 13:13:47 -08:00
kasan, mm, arm64: tag non slab memory allocated via pagealloc
2018-12-28 12:11:44 -08:00
mm: move zone watermark accesses behind an accessor
2018-12-28 12:11:48 -08:00
mm/debug.c: make "migrate_reason_names[]" const char *
2018-12-28 12:11:48 -08:00
mm/: remove caller signal_pending branch predictions
2019-01-04 13:13:48 -08:00
Merge branch 'akpm' (patches from Andrew)
2019-01-05 09:16:18 -08:00
mm/gup_benchmark.c: prevent integer overflow in ioctl
2018-10-31 08:54:12 -07:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm
2018-12-28 12:11:52 -08:00
mm: treewide: remove unused address argument from pte_alloc functions
2019-01-04 13:13:47 -08:00
mm/: remove caller signal_pending branch predictions
2019-01-04 13:13:48 -08:00
mm: use alloc_flags to record if kswapd can wake
2018-12-28 12:11:48 -08:00
ksm: replace jhash2 with xxhash
2018-12-28 12:11:46 -08:00
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
2018-12-28 12:11:50 -08:00
kmemleak: add config to select auto scan
2018-12-28 12:11:51 -08:00
ksm: react on changing "sleep_millisecs" parameter faster
2018-12-28 12:11:51 -08:00
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
2018-12-28 12:11:50 -08:00
mm: remove nobootmem
2018-10-31 08:54:16 -07:00
mm/memblock.c: skip kmemleak for kasan_init()
2018-12-28 12:11:49 -08:00
memcg, oom: notify on oom killer invocation from the charge path
2018-12-28 12:11:52 -08:00
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
2018-12-28 12:11:51 -08:00
mm: treewide: remove unused address argument from pte_alloc functions
2019-01-04 13:13:47 -08:00
mm, memory_hotplug: deobfuscate migration part of offlining
2018-12-28 12:11:50 -08:00
Revert "mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask"
2018-12-08 10:26:20 -08:00
mm: treewide: remove unused address argument from pte_alloc functions
2019-01-04 13:13:47 -08:00
Change mincore() to count "mapped" pages rather than "cached" pages
2019-01-06 13:43:02 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
mm/mmap.c: remove verify_mm_writelocked()
2018-12-28 12:11:47 -08:00
mm: Replace call_rcu_sched() with call_rcu()
2018-11-27 09:21:46 -08:00
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
2018-12-28 12:11:50 -08:00
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
2018-12-28 12:11:50 -08:00
mm: speed up mremap by 20x on large regions
2019-01-04 13:13:48 -08:00
mm/gup: cache dev_pagemap while pinning pages
2018-10-26 16:38:15 -07:00
mm/mmu_notifier: use structure for invalidate_range_start/end calls v2
2018-12-28 12:11:50 -08:00
mm/page-writeback.c: don't break integrity writeback on ->writepage() error
2018-12-28 12:11:49 -08:00
mm/page_alloc.c: allow error injection
2018-12-28 12:11:51 -08:00
mm: remove include/linux/bootmem.h
2018-10-31 08:54:16 -07:00
mm: remove include/linux/bootmem.h
2018-10-31 08:54:16 -07:00
mm/page_io.c: fix polled swap page in
2019-01-04 13:13:48 -08:00
mm: only report isolation failures when offlining memory
2018-12-28 12:11:46 -08:00
mm/page_owner: clamp read count to PAGE_SIZE
2018-12-28 12:11:46 -08:00
virtio, vhost: fixes, tweaks
2018-11-01 14:42:49 -07:00
mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly
2018-10-31 08:54:11 -07:00
percpu: convert spin_lock_irq to spin_lock_irqsave.
2018-12-18 09:04:08 -08:00
Merge branch 'for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu
2018-11-01 09:27:57 -07:00
mm/readahead.c: simplify get_next_ra_size()
2018-12-28 12:11:46 -08:00
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
2018-12-28 12:11:51 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
kasan, mm: change hooks signatures
2018-12-28 12:11:43 -08:00
A fairly normal cycle for documentation stuff. We have a new
2018-12-29 11:21:49 -08:00
mm/slub.c: record final state of slub action in deactivate_slab()
2018-12-28 12:11:46 -08:00
mm: remove include/linux/bootmem.h
2018-10-31 08:54:16 -07:00
mm, sparse: pass nid instead of pgdat to sparse_add_one_section()
2018-12-28 12:11:49 -08:00
fs: don't open code lru_to_page()
2019-01-04 13:13:48 -08:00
Merge branch 'xarray' of git://git.infradead.org/users/willy/linux-dax
2018-10-28 11:35:40 -07:00
mm, swap: fix swapoff with KSM pages
2018-12-28 12:11:52 -08:00
mm: cleancache: fix corruption on missed inode invalidation
2018-11-30 14:56:14 -08:00
mm: treewide: remove unused address argument from pte_alloc functions
2019-01-04 13:13:47 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
mm: put_and_wait_on_page_locked() while page is migrated
2018-12-28 12:11:48 -08:00
mm: convert zone->managed_pages to atomic variable
2018-12-28 12:11:47 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
z3fold: fix possible reclaim races
2018-11-18 10:15:09 -08:00
mm/zsmalloc.c: fix fall-through annotation
2018-10-26 16:26:35 -07:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
574823bfab