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dumping
commit 04f5866e41fb70690e28397487d8bd8eea7d712a upstream.
The core dumping code has always run without holding the mmap_sem for
writing, despite that is the only way to ensure that the entire vma
layout will not change from under it. Only using some signal
serialization on the processes belonging to the mm is not nearly enough.
This was pointed out earlier. For example in Hugh's post from Jul 2017:
https://lkml.kernel.org/r/alpine.LSU.2.11.1707191716030.2055@eggly.anvils
"Not strictly relevant here, but a related note: I was very surprised
to discover, only quite recently, how handle_mm_fault() may be called
without down_read(mmap_sem) - when core dumping. That seems a
misguided optimization to me, which would also be nice to correct"
In particular because the growsdown and growsup can move the
vm_start/vm_end the various loops the core dump does around the vma will
not be consistent if page faults can happen concurrently.
Pretty much all users calling mmget_not_zero()/get_task_mm() and then
taking the mmap_sem had the potential to introduce unexpected side
effects in the core dumping code.
Adding mmap_sem for writing around the ->core_dump invocation is a
viable long term fix, but it requires removing all copy user and page
faults and to replace them with get_dump_page() for all binary formats
which is not suitable as a short term fix.
For the time being this solution manually covers the places that can
confuse the core dump either by altering the vma layout or the vma flags
while it runs. Once ->core_dump runs under mmap_sem for writing the
function mmget_still_valid() can be dropped.
Allowing mmap_sem protected sections to run in parallel with the
coredump provides some minor parallelism advantage to the swapoff code
(which seems to be safe enough by never mangling any vma field and can
keep doing swapins in parallel to the core dumping) and to some other
corner case.
In order to facilitate the backporting I added "Fixes: 86039bd3b4e6"
however the side effect of this same race condition in /proc/pid/mem
should be reproducible since before 2.6.12-rc2 so I couldn't add any
other "Fixes:" because there's no hash beyond the git genesis commit.
Because find_extend_vma() is the only location outside of the process
context that could modify the "mm" structures under mmap_sem for
reading, by adding the mmget_still_valid() check to it, all other cases
that take the mmap_sem for reading don't need the new check after
mmget_not_zero()/get_task_mm(). The expand_stack() in page fault
context also doesn't need the new check, because all tasks under core
dumping are frozen.
Link: http://lkml.kernel.org/r/20190325224949.11068-1-aarcange@redhat.com
Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jann Horn <jannh@google.com>
Acked-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Drop changes in Infiniband and userfaultfd
- In clear_refs_write(), use up_read() as we never upgrade to a write lock
- Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 0a1d52994d440e21def1c2174932410b4f2a98a1 upstream.
security_mmap_addr() does a capability check with current_cred(), but
we can reach this code from contexts like a VFS write handler where
current_cred() must not be used.
This can be abused on systems without SMAP to make NULL pointer
dereferences exploitable again.
Fixes: 8869477a49c3 ("security: protect from stack expansion into low vm addresses")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 32e4e6d5cbb0c0e427391635991fe65e17797af8 upstream.
expand_stack(vma) fails if address < stack_guard_gap even if there is no
vma->vm_prev. I don't think this makes sense, and we didn't do this
before the recent commit 1be7107fbe18 ("mm: larger stack guard gap,
between vmas").
We do not need a gap in this case, any address is fine as long as
security_mmap_addr() doesn't object.
This also simplifies the code, we know that address >= prev->vm_end and
thus underflow is not possible.
Link: http://lkml.kernel.org/r/20170628175258.GA24881@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit bb177a732c4369bb58a1fe1df8f552b6f0f7db5f upstream.
syzbot has noticed that a specially crafted library can easily hit
VM_BUG_ON in __mm_populate
kernel BUG at mm/gup.c:1242!
invalid opcode: 0000 [#1] SMP
CPU: 2 PID: 9667 Comm: a.out Not tainted 4.18.0-rc3 #644
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
RIP: 0010:__mm_populate+0x1e2/0x1f0
Code: 55 d0 65 48 33 14 25 28 00 00 00 89 d8 75 21 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 18 f1 ff 0f 0b e8 6e 18 f1 ff <0f> 0b 31 db eb c9 e8 93 06 e0 ff 0f 1f 00 55 48 89 e5 53 48 89 fb
Call Trace:
vm_brk_flags+0xc3/0x100
vm_brk+0x1f/0x30
load_elf_library+0x281/0x2e0
__ia32_sys_uselib+0x170/0x1e0
do_fast_syscall_32+0xca/0x420
entry_SYSENTER_compat+0x70/0x7f
The reason is that the length of the new brk is not page aligned when we
try to populate the it. There is no reason to bug on that though.
do_brk_flags already aligns the length properly so the mapping is
expanded as it should. All we need is to tell mm_populate about it.
Besides that there is absolutely no reason to to bug_on in the first
place. The worst thing that could happen is that the last page wouldn't
get populated and that is far from putting system into an inconsistent
state.
Fix the issue by moving the length sanitization code from do_brk_flags
up to vm_brk_flags. The only other caller of do_brk_flags is brk
syscall entry and it makes sure to provide the proper length so t here
is no need for sanitation and so we can use do_brk_flags without it.
Also remove the bogus BUG_ONs.
[osalvador@techadventures.net: fix up vm_brk_flags s@request@len@]
Link: http://lkml.kernel.org/r/20180706090217.GI32658@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: syzbot <syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- There is no do_brk_flags() function; update do_brk()
- do_brk(), vm_brk() return the address on success
- Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit ba093a6d9397da8eafcfbaa7d95bd34255da39a0 upstream.
The vm_brk() alignment calculations should refuse to overflow. The ELF
loader depending on this, but it has been fixed now. No other unsafe
callers have been found.
Link: http://lkml.kernel.org/r/1468014494-25291-3-git-send-email-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Ismael Ripoll Ripoll <iripoll@upv.es>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 423913ad4ae5b3e8fb8983f70969fb522261ba26 upstream.
Commit be83bbf80682 ("mmap: introduce sane default mmap limits") was
introduced to catch problems in various ad-hoc character device drivers
doing mmap and getting the size limits wrong. In the process, it used
"known good" limits for the normal cases of mapping regular files and
block device drivers.
It turns out that the "s_maxbytes" limit was less "known good" than I
thought. In particular, /proc doesn't set it, but exposes one regular
file to mmap: /proc/vmcore. As a result, that file got limited to the
default MAX_INT s_maxbytes value.
This went unnoticed for a while, because apparently the only thing that
needs it is the s390 kernel zfcpdump, but there might be other tools
that use this too.
Vasily suggested just changing s_maxbytes for all of /proc, which isn't
wrong, but makes me nervous at this stage. So instead, just make the
new mmap limit always be MAX_LFS_FILESIZE for regular files, which won't
affect anything else. It wasn't the regular file case I was worried
about.
I'd really prefer for maxsize to have been per-inode, but that is not
how things are today.
Fixes: be83bbf80682 ("mmap: introduce sane default mmap limits")
Reported-by: Vasily Gorbik <gor@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit be83bbf806822b1b89e0a0f23cd87cddc409e429 upstream.
The internal VM "mmap()" interfaces are based on the mmap target doing
everything using page indexes rather than byte offsets, because
traditionally (ie 32-bit) we had the situation that the byte offset
didn't fit in a register. So while the mmap virtual address was limited
by the word size of the architecture, the backing store was not.
So we're basically passing "pgoff" around as a page index, in order to
be able to describe backing store locations that are much bigger than
the word size (think files larger than 4GB etc).
But while this all makes a ton of sense conceptually, we've been dogged
by various drivers that don't really understand this, and internally
work with byte offsets, and then try to work with the page index by
turning it into a byte offset with "pgoff << PAGE_SHIFT".
Which obviously can overflow.
Adding the size of the mapping to it to get the byte offset of the end
of the backing store just exacerbates the problem, and if you then use
this overflow-prone value to check various limits of your device driver
mmap capability, you're just setting yourself up for problems.
The correct thing for drivers to do is to do their limit math in page
indices, the way the interface is designed. Because the generic mmap
code _does_ test that the index doesn't overflow, since that's what the
mmap code really cares about.
HOWEVER.
Finding and fixing various random drivers is a sisyphean task, so let's
just see if we can just make the core mmap() code do the limiting for
us. Realistically, the only "big" backing stores we need to care about
are regular files and block devices, both of which are known to do this
properly, and which have nice well-defined limits for how much data they
can access.
So let's special-case just those two known cases, and then limit other
random mmap users to a backing store that still fits in "unsigned long".
Realistically, that's not much of a limit at all on 64-bit, and on
32-bit architectures the only worry might be the GPU drivers, which can
have big physical address spaces.
To make it possible for drivers like that to say that they are 64-bit
clean, this patch does repurpose the "FMODE_UNSIGNED_OFFSET" bit in the
file flags to allow drivers to mark their file descriptors as safe in
the full 64-bit mmap address space.
[ The timing for doing this is less than optimal, and this should really
go in a merge window. But realistically, this needs wide testing more
than it needs anything else, and being main-line is the only way to do
that.
So the earlier the better, even if it's outside the proper development
cycle - Linus ]
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 27ba0644ea9dfe6e7693abc85837b60e40583b96 upstream.
We don't create non-linear mappings anymore. Let's drop code which
handles them in rmap.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Deleted code is slightly different
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 48f7df329474b49d83d0dffec1b6186647f11976 upstream.
Grazvydas Ignotas has reported a regression in remap_file_pages()
emulation.
Testcase:
#define _GNU_SOURCE
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/mman.h>
#define SIZE (4096 * 3)
int main(int argc, char **argv)
{
unsigned long *p;
long i;
p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
perror("mmap");
return -1;
}
for (i = 0; i < SIZE / 4096; i++)
p[i * 4096 / sizeof(*p)] = i;
if (remap_file_pages(p, 4096, 0, 1, 0)) {
perror("remap_file_pages");
return -1;
}
if (remap_file_pages(p, 4096 * 2, 0, 1, 0)) {
perror("remap_file_pages");
return -1;
}
assert(p[0] == 1);
munmap(p, SIZE);
return 0;
}
The second remap_file_pages() fails with -EINVAL.
The reason is that remap_file_pages() emulation assumes that the target
vma covers whole area we want to over map. That assumption is broken by
first remap_file_pages() call: it split the area into two vma.
The solution is to check next adjacent vmas, if they map the same file
with the same flags.
Fixes: c8d78c1823f4 ("mm: replace remap_file_pages() syscall with emulation")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Grazvydas Ignotas <notasas@gmail.com>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit c8d78c1823f46519473949d33f0d1d33fe21ea16 upstream.
remap_file_pages(2) was invented to be able efficiently map parts of
huge file into limited 32-bit virtual address space such as in database
workloads.
Nonlinear mappings are pain to support and it seems there's no
legitimate use-cases nowadays since 64-bit systems are widely available.
Let's drop it and get rid of all these special-cased code.
The patch replaces the syscall with emulation which creates new VMA on
each remap_file_pages(), unless they it can be merged with an adjacent
one.
I didn't find *any* real code that uses remap_file_pages(2) to test
emulation impact on. I've checked Debian code search and source of all
packages in ALT Linux. No real users: libc wrappers, mentions in
strace, gdb, valgrind and this kind of stuff.
There are few basic tests in LTP for the syscall. They work just fine
with emulation.
To test performance impact, I've written small test case which
demonstrate pretty much worst case scenario: map 4G shmfs file, write to
begin of every page pgoff of the page, remap pages in reverse order,
read every page.
The test creates 1 million of VMAs if emulation is in use, so I had to
set vm.max_map_count to 1100000 to avoid -ENOMEM.
Before: 23.3 ( +- 4.31% ) seconds
After: 43.9 ( +- 0.85% ) seconds
Slowdown: 1.88x
I believe we can live with that.
Test case:
#define _GNU_SOURCE
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/mman.h>
#define MB (1024UL * 1024)
#define SIZE (4096 * MB)
int main(int argc, char **argv)
{
unsigned long *p;
long i, pass;
for (pass = 0; pass < 10; pass++) {
p = mmap(NULL, SIZE, PROT_READ|PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
perror("mmap");
return -1;
}
for (i = 0; i < SIZE / 4096; i++)
p[i * 4096 / sizeof(*p)] = i;
for (i = 0; i < SIZE / 4096; i++) {
if (remap_file_pages(p + i * 4096 / sizeof(*p), 4096,
0, (SIZE - 4096 * (i + 1)) >> 12, 0)) {
perror("remap_file_pages");
return -1;
}
}
for (i = SIZE / 4096 - 1; i >= 0; i--)
assert(p[i * 4096 / sizeof(*p)] == SIZE / 4096 - i - 1);
munmap(p, SIZE);
}
return 0;
}
[akpm@linux-foundation.org: fix spello]
[sasha.levin@oracle.com: initialize populate before usage]
[sasha.levin@oracle.com: grab file ref to prevent race while mmaping]
Signed-off-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Armin Rigo <arigo@tunes.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Deleted code is slightly different
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 37511fb5c91db93d8bd6e3f52f86e5a7ff7cfcdf upstream.
Jörn Engel noticed that the expand_upwards() function might not return
-ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.
Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
which all define TASK_SIZE as 0xffffffff, but since none of those have
an upwards-growing stack we currently have no actual issue.
Nevertheless let's fix this just in case any of the architectures with
an upward-growing stack (currently parisc, metag and partly ia64) define
TASK_SIZE similar.
Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box
Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Jörn Engel <joern@purestorage.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 561b5e0709e4a248c67d024d4d94b6e31e3edf2f upstream.
Commit 1be7107fbe18 ("mm: larger stack guard gap, between vmas") has
introduced a regression in some rust and Java environments which are
trying to implement their own stack guard page. They are punching a new
MAP_FIXED mapping inside the existing stack Vma.
This will confuse expand_{downwards,upwards} into thinking that the
stack expansion would in fact get us too close to an existing non-stack
vma which is a correct behavior wrt safety. It is a real regression on
the other hand.
Let's work around the problem by considering PROT_NONE mapping as a part
of the stack. This is a gros hack but overflowing to such a mapping
would trap anyway an we only can hope that usespace knows what it is
doing and handle it propely.
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Link: http://lkml.kernel.org/r/20170705182849.GA18027@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit bd726c90b6b8ce87602208701b208a208e6d5600 upstream.
Fix expand_upwards() on architectures with an upward-growing stack (parisc,
metag and partly IA-64) to allow the stack to reliably grow exactly up to
the address space limit given by TASK_SIZE.
Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 upstream.
Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
end of unmapped_area_topdown(). Linus points out how MAP_FIXED
(which does not have to respect our stack guard gap intentions)
could result in gap_end below gap_start there. Fix that, and
the similar case in its alternative, unmapped_area().
Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.
This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.
Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.
One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications. For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).
Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.
Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.
Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Hugh Dickins: Backported to 3.16]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 22f6b4d34fcf039c63a94e7670e0da24f8575a5a upstream.
Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.
Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.
Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.
The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.
This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.
Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 3.16: we don't have super_block::s_iflags; use
file_system_type::fs_flags instead]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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commit 12352d3cae2cebe18805a91fab34b534d7444231 upstream.
Sequence vma_lock_anon_vma() - vma_unlock_anon_vma() isn't safe if
anon_vma appeared between lock and unlock. We have to check anon_vma
first or call anon_vma_prepare() to be sure that it's here. There are
only few users of these legacy helpers. Let's get rid of them.
This patch fixes anon_vma lock imbalance in validate_mm(). Write lock
isn't required here, read lock is enough.
And reorders expand_downwards/expand_upwards: security_mmap_addr() and
wrapping-around check don't have to be under anon vma lock.
Link: https://lkml.kernel.org/r/CACT4Y+Y908EjM2z=706dv4rV6dWtxTLK9nFg9_7DhRMLppBo2g@mail.gmail.com
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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commit 3fe89b3e2a7bbf3e97657104b9b33a9d81b950b3 upstream.
I have constantly stumbled upon "kernel BUG at mm/rmap.c:399!" after
upgrading to 3.19 and had no luck with 4.0-rc1 neither.
So, after looking into new logic introduced by commit 7a3ef208e662 ("mm:
prevent endless growth of anon_vma hierarchy"), I found chances are that
unlink_anon_vmas() is called without incrementing dst->anon_vma->degree
in anon_vma_clone() due to allocation failure. If dst->anon_vma is not
NULL in error path, its degree will be incorrectly decremented in
unlink_anon_vmas() and eventually underflow when exiting as a result of
another call to unlink_anon_vmas(). That's how "kernel BUG at
mm/rmap.c:399!" is triggered for me.
This patch fixes the underflow by dropping dst->anon_vma when allocation
fails. It's safe to do so regardless of original value of dst->anon_vma
because dst->anon_vma doesn't have valid meaning if anon_vma_clone()
fails. Besides, callers don't care dst->anon_vma in such case neither.
Also suggested by Michal Hocko, we can clean up vma_adjust() a bit as
anon_vma_clone() now does the work.
[akpm@linux-foundation.org: tweak comment]
Fixes: 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy")
Signed-off-by: Leon Yu <chianglungyu@gmail.com>
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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commit 5703b087dc8eaf47bfb399d6cf512d471beff405 upstream.
I noticed, that "allowed" can easily overflow by falling below 0,
because (total_vm / 32) can be larger than "allowed". The problem
occurs in OVERCOMMIT_NONE mode.
In this case, a huge allocation can success and overcommit the system
(despite OVERCOMMIT_NONE mode). All subsequent allocations will fall
(system-wide), so system become unusable.
The problem was masked out by commit c9b1d0981fcc
("mm: limit growth of 3% hardcoded other user reserve"),
but it's easy to reproduce it on older kernels:
1) set overcommit_memory sysctl to 2
2) mmap() large file multiple times (with VM_SHARED flag)
3) try to malloc() large amount of memory
It also can be reproduced on newer kernels, but miss-configured
sysctl_user_reserve_kbytes is required.
Fix this issue by switching to signed arithmetic here.
[akpm@linux-foundation.org: use min_t]
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Cc: Andrew Shewmaker <agshew@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
|
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commit b800c91a0517071156e772d4fb329ad33590da62 upstream.
Fix for BUG_ON(anon_vma->degree) splashes in unlink_anon_vmas() ("kernel
BUG at mm/rmap.c:399!") caused by commit 7a3ef208e662 ("mm: prevent
endless growth of anon_vma hierarchy")
Anon_vma_clone() is usually called for a copy of source vma in
destination argument. If source vma has anon_vma it should be already
in dst->anon_vma. NULL in dst->anon_vma is used as a sign that it's
called from anon_vma_fork(). In this case anon_vma_clone() finds
anon_vma for reusing.
Vma_adjust() calls it differently and this breaks anon_vma reusing
logic: anon_vma_clone() links vma to old anon_vma and updates degree
counters but vma_adjust() overrides vma->anon_vma right after that. As
a result final unlink_anon_vmas() decrements degree for wrong anon_vma.
This patch assigns ->anon_vma before calling anon_vma_clone().
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-and-tested-by: Chris Clayton <chris2553@googlemail.com>
Reported-and-tested-by: Oded Gabbay <oded.gabbay@amd.com>
Reported-and-tested-by: Chih-Wei Huang <cwhuang@android-x86.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Daniel Forrest <dan.forrest@ssec.wisc.edu>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
|
|
commit 690eac53daff34169a4d74fc7bfbd388c4896abb upstream.
Commit fee7e49d4514 ("mm: propagate error from stack expansion even for
guard page") made sure that we return the error properly for stack
growth conditions. It also theorized that counting the guard page
towards the stack limit might break something, but also said "Let's see
if anybody notices".
Somebody did notice. Apparently android-x86 sets the stack limit very
close to the limit indeed, and including the guard page in the rlimit
check causes the android 'zygote' process problems.
So this adds the (fairly trivial) code to make the stack rlimit check be
against the actual real stack size, rather than the size of the vma that
includes the guard page.
Reported-and-tested-by: Chih-Wei Huang <cwhuang@android-x86.org>
Cc: Jay Foad <jay.foad@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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commit c4ea95d7cd08d9ffd7fa75e6c5e0332d596dd11e upstream.
Andrew Morton noticed that the error return from anon_vma_clone() was
being dropped and replaced with -ENOMEM (which is not itself a bug
because the only error return value from anon_vma_clone() is -ENOMEM).
I did an audit of callers of anon_vma_clone() and discovered an actual
bug where the error return was being lost. In __split_vma(), between
Linux 3.11 and 3.12 the code was changed so the err variable is used
before the call to anon_vma_clone() and the default initial value of
-ENOMEM is overwritten. So a failure of anon_vma_clone() will return
success since err at this point is now zero.
Below is a patch which fixes this bug and also propagates the error
return value from anon_vma_clone() in all cases.
Fixes: ef0855d334e1 ("mm: mempolicy: turn vma_set_policy() into vma_dup_policy()")
Signed-off-by: Daniel Forrest <dan.forrest@ssec.wisc.edu>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tim Hartrick <tim@edgecast.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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commit 6d50e60cd2edb5a57154db5a6f64eef5aa59b751 upstream.
If an anonymous mapping is not allowed to fault thp memory and then
madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never
collapse this memory into thp memory.
This occurs because the madvise(2) handler for thp, hugepage_madvise(),
clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags
until the final action of madvise_behavior(). This causes the
khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when
the vma had previously had VM_NOHUGEPAGE set.
Fix this by passing the correct vma flags to the khugepaged mm slot
handler. There's no chance khugepaged can run on this vma until after
madvise_behavior() returns since we hold mm->mmap_sem.
It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags
in hugepage_advise(), but I didn't want to introduce special case
behavior into madvise_behavior(). I think it's best to just let it
always set vma->vm_flags itself.
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Suleiman Souhlal <suleiman@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ luis: backported to 3.16:
- use VM_BUG_ON() instead of VM_BUG_ON_VMA() ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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|
printk is meant to be used with an associated log level. There are some
instances of printk scattered around the mm code where the log level is
missing. Add a log level and adhere to suggestions by
scripts/checkpatch.pl by moving to the pr_* macros.
Also add the typical pr_fmt definition so that print statements can be
easily traced back to the modules where they occur, correlated one with
another, etc. This will require the removal of some (now redundant)
prefixes on a few print statements.
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
Pull x86 cdso updates from Peter Anvin:
"Vdso cleanups and improvements largely from Andy Lutomirski. This
makes the vdso a lot less ''special''"
* 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso, build: Make LE access macros clearer, host-safe
x86/vdso, build: Fix cross-compilation from big-endian architectures
x86/vdso, build: When vdso2c fails, unlink the output
x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
x86, mm: Replace arch_vma_name with vm_ops->name for vsyscalls
x86, mm: Improve _install_special_mapping and fix x86 vdso naming
mm, fs: Add vm_ops->name as an alternative to arch_vma_name
x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
x86, vdso: Remove vestiges of VDSO_PRELINK and some outdated comments
x86, vdso: Move the vvar and hpet mappings next to the 64-bit vDSO
x86, vdso: Move the 32-bit vdso special pages after the text
x86, vdso: Reimplement vdso.so preparation in build-time C
x86, vdso: Move syscall and sysenter setup into kernel/cpu/common.c
x86, vdso: Clean up 32-bit vs 64-bit vdso params
x86, mm: Ensure correct alignment of the fixmap
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Remove the first mapping check for vma_link. Move the mutex_lock into the
braces when vma->vm_file is true.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Fix a coccinelle error regarding usage of IS_ERR and PTR_ERR instead of
PTR_ERR_OR_ZERO.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
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Using arch_vma_name to give special mappings a name is awkward. x86
currently implements it by comparing the start address of the vma to
the expected address of the vdso. This requires tracking the start
address of special mappings and is probably buggy if a special vma
is split or moved.
Improve _install_special_mapping to just name the vma directly. Use
it to give the x86 vvar area a name, which should make CRIU's life
easier.
As a side effect, the vvar area will show up in core dumps. This
could be considered weird and is fixable.
[hpa: I say we accept this as-is but be prepared to deal with knocking
out the vvars from core dumps if this becomes a problem.]
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/276b39b6b645fb11e345457b503f17b83c2c6fd0.1400538962.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
|
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This patch is a continuation of efforts trying to optimize find_vma(),
avoiding potentially expensive rbtree walks to locate a vma upon faults.
The original approach (https://lkml.org/lkml/2013/11/1/410), where the
largest vma was also cached, ended up being too specific and random,
thus further comparison with other approaches were needed. There are
two things to consider when dealing with this, the cache hit rate and
the latency of find_vma(). Improving the hit-rate does not necessarily
translate in finding the vma any faster, as the overhead of any fancy
caching schemes can be too high to consider.
We currently cache the last used vma for the whole address space, which
provides a nice optimization, reducing the total cycles in find_vma() by
up to 250%, for workloads with good locality. On the other hand, this
simple scheme is pretty much useless for workloads with poor locality.
Analyzing ebizzy runs shows that, no matter how many threads are
running, the mmap_cache hit rate is less than 2%, and in many situations
below 1%.
The proposed approach is to replace this scheme with a small per-thread
cache, maximizing hit rates at a very low maintenance cost.
Invalidations are performed by simply bumping up a 32-bit sequence
number. The only expensive operation is in the rare case of a seq
number overflow, where all caches that share the same address space are
flushed. Upon a miss, the proposed replacement policy is based on the
page number that contains the virtual address in question. Concretely,
the following results are seen on an 80 core, 8 socket x86-64 box:
1) System bootup: Most programs are single threaded, so the per-thread
scheme does improve ~50% hit rate by just adding a few more slots to
the cache.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 50.61% | 19.90 |
| patched | 73.45% | 13.58 |
+----------------+----------+------------------+
2) Kernel build: This one is already pretty good with the current
approach as we're dealing with good locality.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 75.28% | 11.03 |
| patched | 88.09% | 9.31 |
+----------------+----------+------------------+
3) Oracle 11g Data Mining (4k pages): Similar to the kernel build workload.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 70.66% | 17.14 |
| patched | 91.15% | 12.57 |
+----------------+----------+------------------+
4) Ebizzy: There's a fair amount of variation from run to run, but this
approach always shows nearly perfect hit rates, while baseline is just
about non-existent. The amounts of cycles can fluctuate between
anywhere from ~60 to ~116 for the baseline scheme, but this approach
reduces it considerably. For instance, with 80 threads:
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 1.06% | 91.54 |
| patched | 99.97% | 14.18 |
+----------------+----------+------------------+
[akpm@linux-foundation.org: fix nommu build, per Davidlohr]
[akpm@linux-foundation.org: document vmacache_valid() logic]
[akpm@linux-foundation.org: attempt to untangle header files]
[akpm@linux-foundation.org: add vmacache_find() BUG_ON]
[hughd@google.com: add vmacache_valid_mm() (from Oleg)]
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: adjust and enhance comments]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull file locking updates from Jeff Layton:
"Highlights:
- maintainership change for fs/locks.c. Willy's not interested in
maintaining it these days, and is OK with Bruce and I taking it.
- fix for open vs setlease race that Al ID'ed
- cleanup and consolidation of file locking code
- eliminate unneeded BUG() call
- merge of file-private lock implementation"
* 'locks-3.15' of git://git.samba.org/jlayton/linux:
locks: make locks_mandatory_area check for file-private locks
locks: fix locks_mandatory_locked to respect file-private locks
locks: require that flock->l_pid be set to 0 for file-private locks
locks: add new fcntl cmd values for handling file private locks
locks: skip deadlock detection on FL_FILE_PVT locks
locks: pass the cmd value to fcntl_getlk/getlk64
locks: report l_pid as -1 for FL_FILE_PVT locks
locks: make /proc/locks show IS_FILE_PVT locks as type "FLPVT"
locks: rename locks_remove_flock to locks_remove_file
locks: consolidate checks for compatible filp->f_mode values in setlk handlers
locks: fix posix lock range overflow handling
locks: eliminate BUG() call when there's an unexpected lock on file close
locks: add __acquires and __releases annotations to locks_start and locks_stop
locks: remove "inline" qualifier from fl_link manipulation functions
locks: clean up comment typo
locks: close potential race between setlease and open
MAINTAINERS: update entry for fs/locks.c
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Mark function as static in mmap.c because they are not used outside this
file.
This eliminates the following warning in mm/mmap.c:
mm/mmap.c:407:6: warning: no previous prototype for `validate_mm' [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
As Trond pointed out, you can currently deadlock yourself by setting a
file-private lock on a file that requires mandatory locking and then
trying to do I/O on it.
Avoid this problem by plumbing some knowledge of file-private locks into
the mandatory locking code. In order to do this, we must pass down
information about the struct file that's being used to
locks_verify_locked.
Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
|
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The _install_special_mapping() is the new base function for
install_special_mapping(). This function will return a pointer of the
created VMA or a error code in an ERR_PTR()
This new function will be needed by the for the vdso 32 bit support to map the
additonal vvar and hpet pages into the 32 bit address space. This will be done
with io_remap_pfn_range() and remap_pfn_range, which requieres a vm_area_struct.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-3-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
|
|
The VM_SOFTDIRTY bit affects vma merge routine: if two VMAs has all bits
in vm_flags matched except dirty bit the kernel can't longer merge them
and this forces the kernel to generate new VMAs instead.
It finally may lead to the situation when userspace application reaches
vm.max_map_count limit and get crashed in worse case
| (gimp:11768): GLib-ERROR **: gmem.c:110: failed to allocate 4096 bytes
|
| (file-tiff-load:12038): LibGimpBase-WARNING **: file-tiff-load: gimp_wire_read(): error
| xinit: connection to X server lost
|
| waiting for X server to shut down
| /usr/lib64/gimp/2.0/plug-ins/file-tiff-load terminated: Hangup
| /usr/lib64/gimp/2.0/plug-ins/script-fu terminated: Hangup
| /usr/lib64/gimp/2.0/plug-ins/script-fu terminated: Hangup
https://bugzilla.kernel.org/show_bug.cgi?id=67651
https://bugzilla.gnome.org/show_bug.cgi?id=719619#c0
Initial problem came from missed VM_SOFTDIRTY in do_brk() routine but
even if we would set up VM_SOFTDIRTY here, there is still a way to
prevent VMAs from merging: one can call
| echo 4 > /proc/$PID/clear_refs
and clear all VM_SOFTDIRTY over all VMAs presented in memory map, then
new do_brk() will try to extend old VMA and finds that dirty bit doesn't
match thus new VMA will be generated.
As discussed with Pavel, the right approach should be to ignore
VM_SOFTDIRTY bit when we're trying to merge VMAs and if merge successed
we mark extended VMA with dirty bit where needed.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reported-by: Bastian Hougaard <gnome@rvzt.net>
Reported-by: Mel Gorman <mgorman@suse.de>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Code that is obj-y (always built-in) or dependent on a bool Kconfig
(built-in or absent) can never be modular. So using module_init as an
alias for __initcall can be somewhat misleading.
Fix these up now, so that we can relocate module_init from init.h into
module.h in the future. If we don't do this, we'd have to add module.h
to obviously non-modular code, and that would be a worse thing.
The audit targets the following module_init users for change:
mm/ksm.c bool KSM
mm/mmap.c bool MMU
mm/huge_memory.c bool TRANSPARENT_HUGEPAGE
mm/mmu_notifier.c bool MMU_NOTIFIER
Note that direct use of __initcall is discouraged, vs. one of the
priority categorized subgroups. As __initcall gets mapped onto
device_initcall, our use of subsys_initcall (which makes sense for these
files) will thus change this registration from level 6-device to level
4-subsys (i.e. slightly earlier).
However no observable impact of that difference has been observed during
testing.
One might think that core_initcall (l2) or postcore_initcall (l3) would
be more appropriate for anything in mm/ but if we look at some actual
init functions themselves, we see things like:
mm/huge_memory.c --> hugepage_init --> hugepage_init_sysfs
mm/mmap.c --> init_user_reserve --> sysctl_user_reserve_kbytes
mm/ksm.c --> ksm_init --> sysfs_create_group
and hence the choice of subsys_initcall (l4) seems reasonable, and at
the same time minimizes the risk of changing the priority too
drastically all at once. We can adjust further in the future.
Also, several instances of missing ";" at EOL are fixed.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Both do_brk and do_mmap_pgoff verify that we are actually capable of
locking future pages if the corresponding VM_LOCKED flags are used.
Encapsulate this logic into a single mlock_future_check() helper
function.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Some applications that run on HPC clusters are designed around the
availability of RAM and the overcommit ratio is fine tuned to get the
maximum usage of memory without swapping. With growing memory, the
1%-of-all-RAM grain provided by overcommit_ratio has become too coarse
for these workload (on a 2TB machine it represents no less than 20GB).
This patch adds the new overcommit_kbytes sysctl variable that allow a
much finer grain.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With split page table lock for PMD level we can't hold mm->page_table_lock
while updating nr_ptes.
Let's convert it to atomic_long_t to avoid races.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Alex Thorlton <athorlton@sgi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge first patch-bomb from Andrew Morton:
"Quite a lot of other stuff is banked up awaiting further
next->mainline merging, but this batch contains:
- Lots of random misc patches
- OCFS2
- Most of MM
- backlight updates
- lib/ updates
- printk updates
- checkpatch updates
- epoll tweaking
- rtc updates
- hfs
- hfsplus
- documentation
- procfs
- update gcov to gcc-4.7 format
- IPC"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (269 commits)
ipc, msg: fix message length check for negative values
ipc/util.c: remove unnecessary work pending test
devpts: plug the memory leak in kill_sb
./Makefile: export initial ramdisk compression config option
init/Kconfig: add option to disable kernel compression
drivers: w1: make w1_slave::flags long to avoid memory corruption
drivers/w1/masters/ds1wm.cuse dev_get_platdata()
drivers/memstick/core/ms_block.c: fix unreachable state in h_msb_read_page()
drivers/memstick/core/mspro_block.c: fix attributes array allocation
drivers/pps/clients/pps-gpio.c: remove redundant of_match_ptr
kernel/panic.c: reduce 1 byte usage for print tainted buffer
gcov: reuse kbasename helper
kernel/gcov/fs.c: use pr_warn()
kernel/module.c: use pr_foo()
gcov: compile specific gcov implementation based on gcc version
gcov: add support for gcc 4.7 gcov format
gcov: move gcov structs definitions to a gcc version specific file
kernel/taskstats.c: return -ENOMEM when alloc memory fails in add_del_listener()
kernel/taskstats.c: add nla_nest_cancel() for failure processing between nla_nest_start() and nla_nest_end()
kernel/sysctl_binary.c: use scnprintf() instead of snprintf()
...
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The same calculation is currently done in three differents places.
Factor that code so future changes has to be made at only one place.
[akpm@linux-foundation.org: uninline vm_commit_limit()]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch fixes the problem that get_unmapped_area() can return illegal
address and result in failing mmap(2) etc.
In case that the address higher than PAGE_SIZE is set to
/proc/sys/vm/mmap_min_addr, the address lower than mmap_min_addr can be
returned by get_unmapped_area(), even if you do not pass any virtual
address hint (i.e. the second argument).
This is because the current get_unmapped_area() code does not take into
account mmap_min_addr.
This leads to two actual problems as follows:
1. mmap(2) can fail with EPERM on the process without CAP_SYS_RAWIO,
although any illegal parameter is not passed.
2. The bottom-up search path after the top-down search might not work in
arch_get_unmapped_area_topdown().
Note: The first and third chunk of my patch, which changes "len" check,
are for more precise check using mmap_min_addr, and not for solving the
above problem.
[How to reproduce]
--- test.c -------------------------------------------------
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/errno.h>
int main(int argc, char *argv[])
{
void *ret = NULL, *last_map;
size_t pagesize = sysconf(_SC_PAGESIZE);
do {
last_map = ret;
ret = mmap(0, pagesize, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
// printf("ret=%p\n", ret);
} while (ret != MAP_FAILED);
if (errno != ENOMEM) {
printf("ERR: unexpected errno: %d (last map=%p)\n",
errno, last_map);
}
return 0;
}
---------------------------------------------------------------
$ gcc -m32 -o test test.c
$ sudo sysctl -w vm.mmap_min_addr=65536
vm.mmap_min_addr = 65536
$ ./test (run as non-priviledge user)
ERR: unexpected errno: 1 (last map=0x10000)
Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is more or less the generic variant of commit 41aacc1eea64 ("x86
get_unmapped_area: Access mmap_legacy_base through mm_struct member").
So effectively architectures which use an own arch_pick_mmap_layout()
implementation but call the generic arch_get_unmapped_area() now can
also randomize their mmap_base.
All architectures which have an own arch_pick_mmap_layout() and call the
generic arch_get_unmapped_area() (arm64, s390, tile) currently set
mmap_base to TASK_UNMAPPED_BASE. This is also true for the generic
arch_pick_mmap_layout() function. So this change is a no-op currently.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Radu Caragea <sinaelgl@gmail.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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pgoff is not used after the statement "pgoff = vma->vm_pgoff;", so the
assignment is redundant.
Signed-off-by: Yanchuan Nian <ycnian@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pavel reported that in case if vma area get unmapped and then mapped (or
expanded) in-place, the soft dirty tracker won't be able to recognize this
situation since it works on pte level and ptes are get zapped on unmap,
loosing soft dirty bit of course.
So to resolve this situation we need to track actions on vma level, there
VM_SOFTDIRTY flag comes in. When new vma area created (or old expanded)
we set this bit, and keep it here until application calls for clearing
soft dirty bit.
Thus when user space application track memory changes now it can detect if
vma area is renewed.
Reported-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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correct_wcount and inode in mmap_region() just complicate the code. This
boolean was needed previously, when deny_write_access() was called before
vma_merge(), now we can simply check VM_DENYWRITE and do
allow_write_access() if it is set.
allow_write_access() checks file != NULL, so this is safe even if it was
possible to use VM_DENYWRITE && !file. Just we need to ensure we use the
same file which was deny_write_access()'ed, so the patch also moves "file
= vma->vm_file" down after allow_write_access().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Colin Cross <ccross@android.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Simple cleanup. Move "struct inode *inode" variable into "if (file)"
block to simplify the code and avoid the unnecessary check.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Colin Cross <ccross@android.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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mmap() doesn't allow the non-anonymous mappings with VM_GROWS* bit set.
In particular this means that mmap_region()->vma_merge(file, vm_flags)
must always fail if "vm_flags & VM_GROWS" is set incorrectly.
So it does not make sense to check VM_GROWS* after we already allocated
the new vma, the only caller, do_mmap_pgoff(), which can pass this flag
can do the check itself.
And this looks a bit more correct, mmap_region() already unmapped the
old mapping at this stage. But if mmap() is going to fail, it should
avoid do_munmap() if possible.
Note: we check VM_GROWS at the end to ensure that do_mmap_pgoff() won't
return EINVAL in the case when it currently returns another error code.
Many thanks to Hugh who nacked the buggy v1.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Simple cleanup. Every user of vma_set_policy() does the same work, this
looks a bit annoying imho. And the new trivial helper which does
mpol_dup() + vma_set_policy() to simplify the callers.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Ben Tebulin reported:
"Since v3.7.2 on two independent machines a very specific Git
repository fails in 9/10 cases on git-fsck due to an SHA1/memory
failures. This only occurs on a very specific repository and can be
reproduced stably on two independent laptops. Git mailing list ran
out of ideas and for me this looks like some very exotic kernel issue"
and bisected the failure to the backport of commit 53a59fc67f97 ("mm:
limit mmu_gather batching to fix soft lockups on !CONFIG_PREEMPT").
That commit itself is not actually buggy, but what it does is to make it
much more likely to hit the partial TLB invalidation case, since it
introduces a new case in tlb_next_batch() that previously only ever
happened when running out of memory.
The real bug is that the TLB gather virtual memory range setup is subtly
buggered. It was introduced in commit 597e1c3580b7 ("mm/mmu_gather:
enable tlb flush range in generic mmu_gather"), and the range handling
was already fixed at least once in commit e6c495a96ce0 ("mm: fix the TLB
range flushed when __tlb_remove_page() runs out of slots"), but that fix
was not complete.
The problem with the TLB gather virtual address range is that it isn't
set up by the initial tlb_gather_mmu() initialization (which didn't get
the TLB range information), but it is set up ad-hoc later by the
functions that actually flush the TLB. And so any such case that forgot
to update the TLB range entries would potentially miss TLB invalidates.
Rather than try to figure out exactly which particular ad-hoc range
setup was missing (I personally suspect it's the hugetlb case in
zap_huge_pmd(), which didn't have the same logic as zap_pte_range()
did), this patch just gets rid of the problem at the source: make the
TLB range information available to tlb_gather_mmu(), and initialize it
when initializing all the other tlb gather fields.
This makes the patch larger, but conceptually much simpler. And the end
result is much more understandable; even if you want to play games with
partial ranges when invalidating the TLB contents in chunks, now the
range information is always there, and anybody who doesn't want to
bother with it won't introduce subtle bugs.
Ben verified that this fixes his problem.
Reported-bisected-and-tested-by: Ben Tebulin <tebulin@googlemail.com>
Build-testing-by: Stephen Rothwell <sfr@canb.auug.org.au>
Build-testing-by: Richard Weinberger <richard.weinberger@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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