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
cma.h
compaction.c
debug_page_ref.c
debug.c
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
hmm.c
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
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
memcontrol.c
memfd.c
memory_hotplug.c
memory-failure.c
memory.c	mm: treewide: remove unused address argument from pte_alloc functions	2019-01-04 13:13:47 -08:00
mempolicy.c
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
mmap.c
mmu_context.c
mmu_gather.c
mmu_notifier.c
mmzone.c
mprotect.c
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
page_alloc.c
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
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
pgtable-generic.c
process_vm_access.c
quicklist.c
readahead.c
rmap.c
rodata_test.c
shmem.c
slab_common.c	A fairly normal cycle for documentation stuff. We have a new	2018-12-29 11:21:49 -08:00
slab.c
slab.h
slob.c
slub.c
sparse-vmemmap.c
sparse.c
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
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
vmacache.c
vmalloc.c
vmpressure.c
vmscan.c
vmstat.c
workingset.c
z3fold.c
zbud.c
zpool.c
zsmalloc.c
zswap.c