... instead of open-coding the call of ->read() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Several modules may need max_mapnr, so export, the related error with allmodconfig under c6x: MODPOST 3327 modules ERROR: "max_mapnr" [fs/pstore/ramoops.ko] undefined! ERROR: "max_mapnr" [drivers/media/v4l2-core/videobuf2-dma-contig.ko] undefined! Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Maxime reported the following memory leak regression due to commit
dbc8358c7237 ("mm/nommu: use alloc_pages_exact() rather than its own
implementation").
On v3.19, I am facing a memory leak. Each time I run a command one page
is lost. Here an example with busybox's free command:
/ # free
total used free shared buffers cached
Mem: 7928 1972 5956 0 0 492
-/+ buffers/cache: 1480 6448
/ # free
total used free shared buffers cached
Mem: 7928 1976 5952 0 0 492
-/+ buffers/cache: 1484 6444
/ # free
total used free shared buffers cached
Mem: 7928 1980 5948 0 0 492
-/+ buffers/cache: 1488 6440
/ # free
total used free shared buffers cached
Mem: 7928 1984 5944 0 0 492
-/+ buffers/cache: 1492 6436
/ # free
total used free shared buffers cached
Mem: 7928 1988 5940 0 0 492
-/+ buffers/cache: 1496 6432
At some point, the system fails to sastisfy 256KB allocations:
free: page allocation failure: order:6, mode:0xd0
CPU: 0 PID: 67 Comm: free Not tainted 3.19.0-05389-gacf2cf1-dirty #64
Hardware name: STM32 (Device Tree Support)
show_stack+0xb/0xc
warn_alloc_failed+0x97/0xbc
__alloc_pages_nodemask+0x295/0x35c
__get_free_pages+0xb/0x24
alloc_pages_exact+0x19/0x24
do_mmap_pgoff+0x423/0x658
vm_mmap_pgoff+0x3f/0x4e
load_flat_file+0x20d/0x4f8
load_flat_binary+0x3f/0x26c
search_binary_handler+0x51/0xe4
do_execveat_common+0x271/0x35c
do_execve+0x19/0x1c
ret_fast_syscall+0x1/0x4a
Mem-info:
Normal per-cpu:
CPU 0: hi: 0, btch: 1 usd: 0
active_anon:0 inactive_anon:0 isolated_anon:0
active_file:0 inactive_file:0 isolated_file:0
unevictable:123 dirty:0 writeback:0 unstable:0
free:1515 slab_reclaimable:17 slab_unreclaimable:139
mapped:0 shmem:0 pagetables:0 bounce:0
free_cma:0
Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks
lowmem_reserve[]: 0 0
Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB
123 total pagecache pages
2048 pages of RAM
1538 free pages
66 reserved pages
109 slab pages
-46 pages shared
0 pages swap cached
nommu: Allocation of length 221184 from process 67 (free) failed
Normal per-cpu:
CPU 0: hi: 0, btch: 1 usd: 0
active_anon:0 inactive_anon:0 isolated_anon:0
active_file:0 inactive_file:0 isolated_file:0
unevictable:123 dirty:0 writeback:0 unstable:0
free:1515 slab_reclaimable:17 slab_unreclaimable:139
mapped:0 shmem:0 pagetables:0 bounce:0
free_cma:0
Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks
lowmem_reserve[]: 0 0
Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB
123 total pagecache pages
Unable to allocate RAM for process text/data, errno 12 SEGV
This problem happens because we allocate ordered page through
__get_free_pages() in do_mmap_private() in some cases and we try to free
individual pages rather than ordered page in free_page_series(). In
this case, freeing pages whose refcount is not 0 won't be freed to the
page allocator so memory leak happens.
To fix the problem, this patch changes __get_free_pages() to
alloc_pages_exact() since alloc_pages_exact() returns
physically-contiguous pages but each pages are refcounted.
Fixes: dbc8358c7237 ("mm/nommu: use alloc_pages_exact() rather than its own implementation").
Reported-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Tested-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org> [3.19]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull backing device changes from Jens Axboe: "This contains a cleanup of how the backing device is handled, in preparation for a rework of the life time rules. In this part, the most important change is to split the unrelated nommu mmap flags from it, but also removing a backing_dev_info pointer from the address_space (and inode), and a cleanup of other various minor bits. Christoph did all the work here, I just fixed an oops with pages that have a swap backing. Arnd fixed a missing export, and Oleg killed the lustre backing_dev_info from staging. Last patch was from Al, unexporting parts that are now no longer needed outside" * 'for-3.20/bdi' of git://git.kernel.dk/linux-block: Make super_blocks and sb_lock static mtd: export new mtd_mmap_capabilities fs: make inode_to_bdi() handle NULL inode staging/lustre/llite: get rid of backing_dev_info fs: remove default_backing_dev_info fs: don't reassign dirty inodes to default_backing_dev_info nfs: don't call bdi_unregister ceph: remove call to bdi_unregister fs: remove mapping->backing_dev_info fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info nilfs2: set up s_bdi like the generic mount_bdev code block_dev: get bdev inode bdi directly from the block device block_dev: only write bdev inode on close fs: introduce f_op->mmap_capabilities for nommu mmap support fs: kill BDI_CAP_SWAP_BACKED fs: deduplicate noop_backing_dev_info
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.
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some callers (like KVM) may want to set the gup_flags like FOLL_HWPOSION to get a proper -EHWPOSION retval instead of -EFAULT to take a more appropriate action if get_user_pages runs into a memory failure. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Peter Feiner <pfeiner@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
FAULT_FOLL_ALLOW_RETRY allows the page fault to drop the mmap_sem for
reading to reduce the mmap_sem contention (for writing), like while
waiting for I/O completion. The problem is that right now practically no
get_user_pages call uses FAULT_FOLL_ALLOW_RETRY, so we're not leveraging
that nifty feature.
Andres fixed it for the KVM page fault. However get_user_pages_fast
remains uncovered, and 99% of other get_user_pages aren't using it either
(the only exception being FOLL_NOWAIT in KVM which is really nonblocking
and in fact it doesn't even release the mmap_sem).
So this patchsets extends the optimization Andres did in the KVM page
fault to the whole kernel. It makes most important places (including
gup_fast) to use FAULT_FOLL_ALLOW_RETRY to reduce the mmap_sem hold times
during I/O.
The only few places that remains uncovered are drivers like v4l and other
exceptions that tends to work on their own memory and they're not working
on random user memory (for example like O_DIRECT that uses gup_fast and is
fully covered by this patch).
A follow up patch should probably also add a printk_once warning to
get_user_pages that should go obsolete and be phased out eventually. The
"vmas" parameter of get_user_pages makes it fundamentally incompatible
with FAULT_FOLL_ALLOW_RETRY (vmas array becomes meaningless the moment the
mmap_sem is released).
While this is just an optimization, this becomes an absolute requirement
for the userfaultfd feature http://lwn.net/Articles/615086/ .
The userfaultfd allows to block the page fault, and in order to do so I
need to drop the mmap_sem first. So this patch also ensures that all
memory where userfaultfd could be registered by KVM, the very first fault
(no matter if it is a regular page fault, or a get_user_pages) always has
FAULT_FOLL_ALLOW_RETRY set. Then the userfaultfd blocks and it is waken
only when the pagetable is already mapped. The second fault attempt after
the wakeup doesn't need FAULT_FOLL_ALLOW_RETRY, so it's ok to retry
without it.
This patch (of 5):
We can leverage the VM_FAULT_RETRY functionality in the page fault paths
better by using either get_user_pages_locked or get_user_pages_unlocked.
The former allows conversion of get_user_pages invocations that will have
to pass a "&locked" parameter to know if the mmap_sem was dropped during
the call. Example from:
down_read(&mm->mmap_sem);
do_something()
get_user_pages(tsk, mm, ..., pages, NULL);
up_read(&mm->mmap_sem);
to:
int locked = 1;
down_read(&mm->mmap_sem);
do_something()
get_user_pages_locked(tsk, mm, ..., pages, &locked);
if (locked)
up_read(&mm->mmap_sem);
The latter is suitable only as a drop in replacement of the form:
down_read(&mm->mmap_sem);
get_user_pages(tsk, mm, ..., pages, NULL);
up_read(&mm->mmap_sem);
into:
get_user_pages_unlocked(tsk, mm, ..., pages);
Where tsk, mm, the intermediate "..." paramters and "pages" can be any
value as before. Just the last parameter of get_user_pages (vmas) must be
NULL for get_user_pages_locked|unlocked to be usable (the latter original
form wouldn't have been safe anyway if vmas wasn't null, for the former we
just make it explicit by dropping the parameter).
If vmas is not NULL these two methods cannot be used.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Reviewed-by: Peter Feiner <pfeiner@google.com>
Reviewed-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>
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>
The symbol 'high_memory' is provided on both MMU- and NOMMU-kernels, but only one of them is exported, which leads to module build errors in drivers that work fine built-in: ERROR: "high_memory" [drivers/net/virtio_net.ko] undefined! ERROR: "high_memory" [drivers/net/ppp/ppp_mppe.ko] undefined! ERROR: "high_memory" [drivers/mtd/nand/nand.ko] undefined! ERROR: "high_memory" [crypto/tcrypt.ko] undefined! ERROR: "high_memory" [crypto/cts.ko] undefined! This exports the symbol to get these to work on NOMMU as well. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Greg Ungerer <gerg@uclinux.org> 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>
Since "BDI: Provide backing device capability information [try #3]" the backing_dev_info structure also provides flags for the kind of mmap operation available in a nommu environment, which is entirely unrelated to it's original purpose. Introduce a new nommu-only file operation to provide this information to the nommu mmap code instead. Splitting this from the backing_dev_info structure allows to remove lots of backing_dev_info instance that aren't otherwise needed, and entirely gets rid of the concept of providing a backing_dev_info for a character device. It also removes the need for the mtd_inodefs filesystem. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Brian Norris <computersforpeace@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>