This is a patch that provides behavior that is more consistent, and
probably less surprising to users. I consider the change optional, and
welcome opinions about whether it should be applied.
By default, pipes are created with a capacity of 64 kiB. However,
/proc/sys/fs/pipe-max-size may be set smaller than this value. In this
scenario, an unprivileged user could thus create a pipe whose initial
capacity exceeds the limit. Therefore, it seems logical to cap the
initial pipe capacity according to the value of pipe-max-size.
The test program shown earlier in this patch series can be used to
demonstrate the effect of the change brought about with this patch:
# cat /proc/sys/fs/pipe-max-size
1048576
# sudo -u mtk ./test_F_SETPIPE_SZ 1
Initial pipe capacity: 65536
# echo 10000 > /proc/sys/fs/pipe-max-size
# cat /proc/sys/fs/pipe-max-size
16384
# sudo -u mtk ./test_F_SETPIPE_SZ 1
Initial pipe capacity: 16384
# ./test_F_SETPIPE_SZ 1
Initial pipe capacity: 65536
The last two executions of 'test_F_SETPIPE_SZ' show that pipe-max-size
caps the initial allocation for a new pipe for unprivileged users, but
not for privileged users.
Link: http://lkml.kernel.org/r/31dc7064-2a17-9c5b-1df1-4e3012ee992c@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is an optional patch, to provide a small performance
improvement. Alter account_pipe_buffers() so that it returns the
new value in user->pipe_bufs. This means that we can refactor
too_many_pipe_buffers_soft() and too_many_pipe_buffers_hard() to
avoid the costs of repeated use of atomic_long_read() to get the
value user->pipe_bufs.
Link: http://lkml.kernel.org/r/93e5f193-1e5e-3e1f-3a20-eae79b7e1310@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The limit checking in alloc_pipe_info() (used by pipe(2) and when
opening a FIFO) has the following problems:
(1) When checking capacity required for the new pipe, the checks against
the limit in /proc/sys/fs/pipe-user-pages-{soft,hard} are made
against existing consumption, and exclude the memory required for
the new pipe capacity. As a consequence: (1) the memory allocation
throttling provided by the soft limit does not kick in quite as
early as it should, and (2) the user can overrun the hard limit.
(2) As currently implemented, accounting and checking against the limits
is done as follows:
(a) Test whether the user has exceeded the limit.
(b) Make new pipe buffer allocation.
(c) Account new allocation against the limits.
This is racey. Multiple processes may pass point (a) simultaneously,
and then allocate pipe buffers that are accounted for only in step
(c). The race means that the user's pipe buffer allocation could be
pushed over the limit (by an arbitrary amount, depending on how
unlucky we were in the race). [Thanks to Vegard Nossum for spotting
this point, which I had missed.]
This patch addresses the above problems as follows:
* Alter the checks against limits to include the memory required for the
new pipe.
* Re-order the accounting step so that it precedes the buffer allocation.
If the accounting step determines that a limit has been reached, revert
the accounting and cause the operation to fail.
Link: http://lkml.kernel.org/r/8ff3e9f9-23f6-510c-644f-8e70cd1c0bd9@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace an 'if' block that covers most of the code in this function
with a 'goto'. This makes the code a little simpler to read, and also
simplifies the next patch (fix limit checking in alloc_pipe_info())
Link: http://lkml.kernel.org/r/aef030c1-0257-98a9-4988-186efa48530c@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The limit checking in pipe_set_size() (used by fcntl(F_SETPIPE_SZ))
has the following problems:
(1) When increasing the pipe capacity, the checks against the limits in
/proc/sys/fs/pipe-user-pages-{soft,hard} are made against existing
consumption, and exclude the memory required for the increased pipe
capacity. The new increase in pipe capacity can then push the total
memory used by the user for pipes (possibly far) over a limit. This
can also trigger the problem described next.
(2) The limit checks are performed even when the new pipe capacity is
less than the existing pipe capacity. This can lead to problems if a
user sets a large pipe capacity, and then the limits are lowered,
with the result that the user will no longer be able to decrease the
pipe capacity.
(3) As currently implemented, accounting and checking against the
limits is done as follows:
(a) Test whether the user has exceeded the limit.
(b) Make new pipe buffer allocation.
(c) Account new allocation against the limits.
This is racey. Multiple processes may pass point (a)
simultaneously, and then allocate pipe buffers that are accounted
for only in step (c). The race means that the user's pipe buffer
allocation could be pushed over the limit (by an arbitrary amount,
depending on how unlucky we were in the race). [Thanks to Vegard
Nossum for spotting this point, which I had missed.]
This patch addresses the above problems as follows:
* Perform checks against the limits only when increasing a pipe's
capacity; an unprivileged user can always decrease a pipe's capacity.
* Alter the checks against limits to include the memory required for
the new pipe capacity.
* Re-order the accounting step so that it precedes the buffer
allocation. If the accounting step determines that a limit has
been reached, revert the accounting and cause the operation to fail.
The program below can be used to demonstrate problems 1 and 2, and the
effect of the fix. The program takes one or more command-line arguments.
The first argument specifies the number of pipes that the program should
create. The remaining arguments are, alternately, pipe capacities that
should be set using fcntl(F_SETPIPE_SZ), and sleep intervals (in
seconds) between the fcntl() operations. (The sleep intervals allow the
possibility to change the limits between fcntl() operations.)
Problem 1
=========
Using the test program on an unpatched kernel, we first set some
limits:
# echo 0 > /proc/sys/fs/pipe-user-pages-soft
# echo 1000000000 > /proc/sys/fs/pipe-max-size
# echo 10000 > /proc/sys/fs/pipe-user-pages-hard # 40.96 MB
Then show that we can set a pipe with capacity (100MB) that is
over the hard limit
# sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000
Initial pipe capacity: 65536
Loop 1: set pipe capacity to 100000000 bytes
F_SETPIPE_SZ returned 134217728
Now set the capacity to 100MB twice. The second call fails (which is
probably surprising to most users, since it seems like a no-op):
# sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000 0 100000000
Initial pipe capacity: 65536
Loop 1: set pipe capacity to 100000000 bytes
F_SETPIPE_SZ returned 134217728
Loop 2: set pipe capacity to 100000000 bytes
Loop 2, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted
With a patched kernel, setting a capacity over the limit fails at the
first attempt:
# echo 0 > /proc/sys/fs/pipe-user-pages-soft
# echo 1000000000 > /proc/sys/fs/pipe-max-size
# echo 10000 > /proc/sys/fs/pipe-user-pages-hard
# sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000
Initial pipe capacity: 65536
Loop 1: set pipe capacity to 100000000 bytes
Loop 1, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted
There is a small chance that the change to fix this problem could
break user-space, since there are cases where fcntl(F_SETPIPE_SZ)
calls that previously succeeded might fail. However, the chances are
small, since (a) the pipe-user-pages-{soft,hard} limits are new (in
4.5), and the default soft/hard limits are high/unlimited. Therefore,
it seems warranted to make these limits operate more precisely (and
behave more like what users probably expect).
Problem 2
=========
Running the test program on an unpatched kernel, we first set some limits:
# getconf PAGESIZE
4096
# echo 0 > /proc/sys/fs/pipe-user-pages-soft
# echo 1000000000 > /proc/sys/fs/pipe-max-size
# echo 10000 > /proc/sys/fs/pipe-user-pages-hard # 40.96 MB
Now perform two fcntl(F_SETPIPE_SZ) operations on a single pipe,
first setting a pipe capacity (10MB), sleeping for a few seconds,
during which time the hard limit is lowered, and then set pipe
capacity to a smaller amount (5MB):
# sudo -u mtk ./test_F_SETPIPE_SZ 1 10000000 15 5000000 &
[1] 748
# Initial pipe capacity: 65536
Loop 1: set pipe capacity to 10000000 bytes
F_SETPIPE_SZ returned 16777216
Sleeping 15 seconds
# echo 1000 > /proc/sys/fs/pipe-user-pages-hard # 4.096 MB
# Loop 2: set pipe capacity to 5000000 bytes
Loop 2, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted
In this case, the user should be able to lower the limit.
With a kernel that has the patch below, the second fcntl()
succeeds:
# echo 0 > /proc/sys/fs/pipe-user-pages-soft
# echo 1000000000 > /proc/sys/fs/pipe-max-size
# echo 10000 > /proc/sys/fs/pipe-user-pages-hard
# sudo -u mtk ./test_F_SETPIPE_SZ 1 10000000 15 5000000 &
[1] 3215
# Initial pipe capacity: 65536
# Loop 1: set pipe capacity to 10000000 bytes
F_SETPIPE_SZ returned 16777216
Sleeping 15 seconds
# echo 1000 > /proc/sys/fs/pipe-user-pages-hard
# Loop 2: set pipe capacity to 5000000 bytes
F_SETPIPE_SZ returned 8388608
8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---
/* test_F_SETPIPE_SZ.c
(C) 2016, Michael Kerrisk; licensed under GNU GPL version 2 or later
Test operation of fcntl(F_SETPIPE_SZ) for setting pipe capacity
and interactions with limits defined by /proc/sys/fs/pipe-* files.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
int (*pfd)[2];
int npipes;
int pcap, rcap;
int j, p, s, stime, loop;
if (argc < 2) {
fprintf(stderr, "Usage: %s num-pipes "
"[pipe-capacity sleep-time]...\n", argv[0]);
exit(EXIT_FAILURE);
}
npipes = atoi(argv[1]);
pfd = calloc(npipes, sizeof (int [2]));
if (pfd == NULL) {
perror("calloc");
exit(EXIT_FAILURE);
}
for (j = 0; j < npipes; j++) {
if (pipe(pfd[j]) == -1) {
fprintf(stderr, "Loop %d: pipe() failed: ", j);
perror("pipe");
exit(EXIT_FAILURE);
}
}
printf("Initial pipe capacity: %d\n", fcntl(pfd[0][0], F_GETPIPE_SZ));
for (j = 2; j < argc; j += 2 ) {
loop = j / 2;
pcap = atoi(argv[j]);
printf(" Loop %d: set pipe capacity to %d bytes\n", loop, pcap);
for (p = 0; p < npipes; p++) {
s = fcntl(pfd[p][0], F_SETPIPE_SZ, pcap);
if (s == -1) {
fprintf(stderr, " Loop %d, pipe %d: F_SETPIPE_SZ "
"failed: ", loop, p);
perror("fcntl");
exit(EXIT_FAILURE);
}
if (p == 0) {
printf(" F_SETPIPE_SZ returned %d\n", s);
rcap = s;
} else {
if (s != rcap) {
fprintf(stderr, " Loop %d, pipe %d: F_SETPIPE_SZ "
"unexpected return: %d\n", loop, p, s);
exit(EXIT_FAILURE);
}
}
stime = (j + 1 < argc) ? atoi(argv[j + 1]) : 0;
if (stime > 0) {
printf(" Sleeping %d seconds\n", stime);
sleep(stime);
}
}
}
exit(EXIT_SUCCESS);
}
8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---
Patch history:
v2
* Switch order of test in 'if' statement to avoid function call
(to capability()) in normal path. [This is a fix to a preexisting
wart in the code. Thanks to Willy Tarreau]
* Perform (size > pipe_max_size) check before calling
account_pipe_buffers(). [Thanks to Vegard Nossum]
Quoting Vegard:
The potential problem happens if the user passes a very large number
which will overflow pipe->user->pipe_bufs.
On 32-bit, sizeof(int) == sizeof(long), so if they pass arg = INT_MAX
then round_pipe_size() returns INT_MAX. Although it's true that the
accounting is done in terms of pages and not bytes, so you'd need on
the order of (1 << 13) = 8192 processes hitting the limit at the same
time in order to make it overflow, which seems a bit unlikely.
(See https://lkml.org/lkml/2016/8/12/215 for another discussion on the
limit checking)
Link: http://lkml.kernel.org/r/1e464945-536b-2420-798b-e77b9c7e8593@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a preparatory patch for following work. account_pipe_buffers()
performs accounting in the 'user_struct'. There is no need to pass a
pointer to a 'pipe_inode_info' struct (which is then dereferenced to
obtain a pointer to the 'user' field). Instead, pass a pointer directly
to the 'user_struct'. This change is needed in preparation for a
subsequent patch that the fixes the limit checking in alloc_pipe_info()
(and the resulting code is a little more logical).
Link: http://lkml.kernel.org/r/7277bf8c-a6fc-4a7d-659c-f5b145c981ab@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a preparatory patch for following work. Move the F_SETPIPE_SZ
limit-checking logic from pipe_fcntl() into pipe_set_size(). This
simplifies the code a little, and allows for reworking required in
a later patch that fixes the limit checking in pipe_set_size()
Link: http://lkml.kernel.org/r/3701b2c5-2c52-2c3e-226d-29b9deb29b50@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "pipe: fix limit handling", v2.
When changing a pipe's capacity with fcntl(F_SETPIPE_SZ), various limits
defined by /proc/sys/fs/pipe-* files are checked to see if unprivileged
users are exceeding limits on memory consumption.
While documenting and testing the operation of these limits I noticed
that, as currently implemented, these checks have a number of problems:
(1) When increasing the pipe capacity, the checks against the limits
in /proc/sys/fs/pipe-user-pages-{soft,hard} are made against
existing consumption, and exclude the memory required for the
increased pipe capacity. The new increase in pipe capacity can then
push the total memory used by the user for pipes (possibly far) over
a limit. This can also trigger the problem described next.
(2) The limit checks are performed even when the new pipe capacity
is less than the existing pipe capacity. This can lead to problems
if a user sets a large pipe capacity, and then the limits are
lowered, with the result that the user will no longer be able to
decrease the pipe capacity.
(3) As currently implemented, accounting and checking against the
limits is done as follows:
(a) Test whether the user has exceeded the limit.
(b) Make new pipe buffer allocation.
(c) Account new allocation against the limits.
This is racey. Multiple processes may pass point (a) simultaneously,
and then allocate pipe buffers that are accounted for only in step
(c). The race means that the user's pipe buffer allocation could be
pushed over the limit (by an arbitrary amount, depending on how
unlucky we were in the race). [Thanks to Vegard Nossum for spotting
this point, which I had missed.]
This patch series addresses these three problems.
This patch (of 8):
This is a minor preparatory patch. After subsequent patches,
round_pipe_size() will be called from pipe_set_size(), so place
round_pipe_size() above pipe_set_size().
Link: http://lkml.kernel.org/r/91a91fdb-a959-ba7f-b551-b62477cc98a1@gmail.com
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cmd part of this struct is the same as an index of itself within
_ioctls[]. In fact this cmd is unused, so we can drop this part.
Link: http://lkml.kernel.org/r/20160831033414.9910.66697.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Having this in autofs_i.h gives illusion that uncommenting this enables
pr_debug(), but it doesn't enable all the pr_debug() in autofs because
inclusion order matters.
XFS has the same DEBUG macro in its core header fs/xfs/xfs.h, however XFS
seems to have a rule to include this prior to other XFS headers as well as
kernel headers. This is not the case with autofs, and DEBUG could be
enabled via Makefile, so autofs should just get rid of this comment to
make the code less confusing. It's a comment, so there is literally no
functional difference.
Link: http://lkml.kernel.org/r/20160831033409.9910.77067.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All other warnings use "cmd(0x%08x)" and this is the only one with
"cmd(%d)". (below comes from my userspace debug program, but not
automount daemon)
[ 1139.905676] autofs4:pid:1640:check_dev_ioctl_version: ioctl control interface version mismatch: kernel(1.0), user(0.0), cmd(-1072131215)
Link: http://lkml.kernel.org/r/20160812024851.12352.75458.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <ikent@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No functional changes, based on the following justification.
1. Make the code more consistent using the ioctl vector _ioctls[],
rather than assigning NULL only for this ioctl command.
2. Remove goto done; for better maintainability in the long run.
3. The existing code is based on the fact that validate_dev_ioctl()
sets ioctl version for any command, but AUTOFS_DEV_IOCTL_VERSION_CMD
should explicitly set it regardless of the default behavior.
Link: http://lkml.kernel.org/r/20160812024846.12352.9885.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <ikent@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The count of miscellaneous device ioctls in fs/autofs4/autofs_i.h is wrong.
The number of ioctls is the difference between AUTOFS_DEV_IOCTL_VERSION_CMD
and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD (14) not the difference between
AUTOFS_IOC_COUNT and 11 (21).
[kusumi.tomohiro@gmail.com: fix typo that made the count macro negative]
Link: http://lkml.kernel.org/r/20160831033420.9910.16809.stgit@pluto.themaw.net
Link: http://lkml.kernel.org/r/20160812024841.12352.11975.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This isn't a return value, so change the message to indicate the status is
the result of may_umount().
(or locate pr_debug() after put_user() with the same message)
Link: http://lkml.kernel.org/r/20160812024836.12352.74628.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <ikent@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These two were left from commit aa55ddf340 ("autofs4: remove unused
ioctls") which removed unused ioctls.
Link: http://lkml.kernel.org/r/20160812024810.12352.96377.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <ikent@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kfree dentry data allocated by autofs4_new_ino() with autofs4_free_ino()
instead of raw kfree. (since we have the interface to free autofs_info*)
This patch was modified to remove the need to set the dentry info field to
NULL dew to a change in the previous patch.
Link: http://lkml.kernel.org/r/20160812024805.12352.43650.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The inode allocation failure case in autofs4_dir_symlink() frees the
autofs dentry info of the dentry without setting ->d_fsdata to NULL.
That could lead to a double free so just get rid of the free and leave it
to ->d_release().
Link: http://lkml.kernel.org/r/20160812024759.12352.10653.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's invalid if the given mode is neither dir nor link, so warn on else
case.
Link: http://lkml.kernel.org/r/20160812024754.12352.8536.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Somewhere along the line the error handling gotos have become incorrect.
Link: http://lkml.kernel.org/r/20160812024749.12352.15100.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch does what the below comment says. It could be and it's
considered better to do this first before various functions get called
during initialization.
/* Couldn't this be tested earlier? */
Link: http://lkml.kernel.org/r/20160812024744.12352.43075.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
autofs4_kill_sb() doesn't need to be declared as extern, and no other
functions in .h are explicitly declared as extern.
Link: http://lkml.kernel.org/r/20160812024739.12352.99354.stgit@pluto.themaw.net
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The select(2) syscall performs a kmalloc(size, GFP_KERNEL) where size grows
with the number of fds passed. We had a customer report page allocation
failures of order-4 for this allocation. This is a costly order, so it might
easily fail, as the VM expects such allocation to have a lower-order fallback.
Such trivial fallback is vmalloc(), as the memory doesn't have to be physically
contiguous and the allocation is temporary for the duration of the syscall
only. There were some concerns, whether this would have negative impact on the
system by exposing vmalloc() to userspace. Although an excessive use of vmalloc
can cause some system wide performance issues - TLB flushes etc. - a large
order allocation is not for free either and an excessive reclaim/compaction can
have a similar effect. Also note that the size is effectively limited by
RLIMIT_NOFILE which defaults to 1024 on the systems I checked. That means the
bitmaps will fit well within single page and thus the vmalloc() fallback could
be only excercised for processes where root allows a higher limit.
Note that the poll(2) syscall seems to use a linked list of order-0 pages, so
it doesn't need this kind of fallback.
[eric.dumazet@gmail.com: fix failure path logic]
[akpm@linux-foundation.org: use proper type for size]
Link: http://lkml.kernel.org/r/20160927084536.5923-1-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After much discussion, it seems that the fallocate feature flag
FALLOC_FL_ZERO_RANGE maps nicely to SCSI WRITE SAME; and the feature
FALLOC_FL_PUNCH_HOLE maps nicely to the devices that have been whitelisted
for zeroing SCSI UNMAP. Punch still requires that FALLOC_FL_KEEP_SIZE is
set. A length that goes past the end of the device will be clamped to the
device size if KEEP_SIZE is set; or will return -EINVAL if not. Both
start and length must be aligned to the device's logical block size.
Since the semantics of fallocate are fairly well established already, wire
up the two pieces. The other fallocate variants (collapse range, insert
range, and allocate blocks) are not supported.
Link: http://lkml.kernel.org/r/147518379992.22791.8849838163218235007.stgit@birch.djwong.org
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com> # tweaked header
Cc: Brian Foster <bfoster@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the dlm_migrate_request_handler(), when `ret' is -EEXIST, the mle
should be freed, otherwise the memory will be leaked.
Link: http://lkml.kernel.org/r/71604351584F6A4EBAE558C676F37CA4A3D3522A@H3CMLB12-EX.srv.huawei-3com.com
Signed-off-by: Guozhonghua <guozhonghua@h3c.com>
Reviewed-by: Mark Fasheh <mfasheh@versity.com>
Cc: Eric Ren <zren@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull networking fixes from David Miller:
1) Netfilter list handling fix, from Linus.
2) RXRPC/AFS bug fixes from David Howells (oops on call to serviceless
endpoints, build warnings, missing notifications, etc.) From David
Howells.
3) Kernel log message missing newlines, from Colin Ian King.
4) Don't enter direct reclaim in netlink dumps, the idea is to use a
high order allocation first and fallback quickly to a 0-order
allocation if such a high-order one cannot be done cheaply and
without reclaim. From Eric Dumazet.
5) Fix firmware download errors in btusb bluetooth driver, from Ethan
Hsieh.
6) Missing Kconfig deps for QCOM_EMAC, from Geert Uytterhoeven.
7) Fix MDIO_XGENE dup Kconfig entry. From Laura Abbott.
8) Constrain ipv6 rtr_solicits sysctl values properly, from Maciej
Żenczykowski.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (65 commits)
netfilter: Fix slab corruption.
be2net: Enable VF link state setting for BE3
be2net: Fix TX stats for TSO packets
be2net: Update Copyright string in be_hw.h
be2net: NCSI FW section should be properly updated with ethtool for BE3
be2net: Provide an alternate way to read pf_num for BEx chips
wan/fsl_ucc_hdlc: Fix size used in dma_free_coherent()
net: macb: NULL out phydev after removing mdio bus
xen-netback: make sure that hashes are not send to unaware frontends
Fixing a bug in team driver due to incorrect 'unsigned int' to 'int' conversion
MAINTAINERS: add myself as a maintainer of xen-netback
ipv6 addrconf: disallow rtr_solicits < -1
Bluetooth: btusb: Fix atheros firmware download error
drivers: net: phy: Correct duplicate MDIO_XGENE entry
ethernet: qualcomm: QCOM_EMAC should depend on HAS_DMA and HAS_IOMEM
net: ethernet: mediatek: remove hwlro property in the device tree
net: ethernet: mediatek: get hw lro capability by the chip id instead of by the dtsi
net: ethernet: mediatek: get the chip id by ETHDMASYS registers
net: bgmac: Fix errant feature flag check
netlink: do not enter direct reclaim from netlink_dump()
...
Pull more vfs updates from Al Viro:
">rename2() work from Miklos + current_time() from Deepa"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Replace current_fs_time() with current_time()
fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
fs: Replace CURRENT_TIME with current_time() for inode timestamps
fs: proc: Delete inode time initializations in proc_alloc_inode()
vfs: Add current_time() api
vfs: add note about i_op->rename changes to porting
fs: rename "rename2" i_op to "rename"
vfs: remove unused i_op->rename
fs: make remaining filesystems use .rename2
libfs: support RENAME_NOREPLACE in simple_rename()
fs: support RENAME_NOREPLACE for local filesystems
ncpfs: fix unused variable warning
Pull vfs xattr updates from Al Viro:
"xattr stuff from Andreas
This completes the switch to xattr_handler ->get()/->set() from
->getxattr/->setxattr/->removexattr"
* 'work.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: Remove {get,set,remove}xattr inode operations
xattr: Stop calling {get,set,remove}xattr inode operations
vfs: Check for the IOP_XATTR flag in listxattr
xattr: Add __vfs_{get,set,remove}xattr helpers
libfs: Use IOP_XATTR flag for empty directory handling
vfs: Use IOP_XATTR flag for bad-inode handling
vfs: Add IOP_XATTR inode operations flag
vfs: Move xattr_resolve_name to the front of fs/xattr.c
ecryptfs: Switch to generic xattr handlers
sockfs: Get rid of getxattr iop
sockfs: getxattr: Fail with -EOPNOTSUPP for invalid attribute names
kernfs: Switch to generic xattr handlers
hfs: Switch to generic xattr handlers
jffs2: Remove jffs2_{get,set,remove}xattr macros
xattr: Remove unnecessary NULL attribute name check
This includes a bug fix for a bad memory access during workqueue
cleanup, which can happen while shutting down the dlm networking
layer.
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Merge tag 'dlm-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm
Pull dlm fix from David Teigland:
"This includes a bug fix for a bad memory access during workqueue
cleanup, which can happen while shutting down the dlm networking
layer"
* tag 'dlm-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm:
dlm: free workqueues after the connections
with maintenance operations offloaded to userspace (Douglas Fuller,
Mike Christie and myself). Another block device bullet is a series
fixing up layering error paths (myself).
On the filesystem side, we've got patches that improve our handling of
buffered vs dio write races (Neil Brown) and a few assorted fixes from
Zheng. Also included a couple of random cleanups and a minor CRUSH
update.
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Merge tag 'ceph-for-4.9-rc1' of git://github.com/ceph/ceph-client
Pull Ceph updates from Ilya Dryomov:
"The big ticket item here is support for rbd exclusive-lock feature,
with maintenance operations offloaded to userspace (Douglas Fuller,
Mike Christie and myself). Another block device bullet is a series
fixing up layering error paths (myself).
On the filesystem side, we've got patches that improve our handling of
buffered vs dio write races (Neil Brown) and a few assorted fixes from
Zheng. Also included a couple of random cleanups and a minor CRUSH
update"
* tag 'ceph-for-4.9-rc1' of git://github.com/ceph/ceph-client: (39 commits)
crush: remove redundant local variable
crush: don't normalize input of crush_ln iteratively
libceph: ceph_build_auth() doesn't need ceph_auth_build_hello()
libceph: use CEPH_AUTH_UNKNOWN in ceph_auth_build_hello()
ceph: fix description for rsize and rasize mount options
rbd: use kmalloc_array() in rbd_header_from_disk()
ceph: use list_move instead of list_del/list_add
ceph: handle CEPH_SESSION_REJECT message
ceph: avoid accessing / when mounting a subpath
ceph: fix mandatory flock check
ceph: remove warning when ceph_releasepage() is called on dirty page
ceph: ignore error from invalidate_inode_pages2_range() in direct write
ceph: fix error handling of start_read()
rbd: add rbd_obj_request_error() helper
rbd: img_data requests don't own their page array
rbd: don't call rbd_osd_req_format_read() for !img_data requests
rbd: rework rbd_img_obj_exists_submit() error paths
rbd: don't crash or leak on errors in rbd_img_obj_parent_read_full_callback()
rbd: move bumping img_request refcount into rbd_obj_request_submit()
rbd: mark the original request as done if stat request fails
...
Pull splice fixups from Al Viro:
"A couple of fixups for interaction of pipe-backed iov_iter with
O_DIRECT reads + constification of a couple of primitives in uio.h
missed by previous rounds.
Kudos to davej - his fuzzing has caught those bugs"
* 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
[btrfs] fix check_direct_IO() for non-iovec iterators
constify iov_iter_count() and iter_is_iovec()
fix ITER_PIPE interaction with direct_IO
Pull misc vfs updates from Al Viro:
"Assorted misc bits and pieces.
There are several single-topic branches left after this (rename2
series from Miklos, current_time series from Deepa Dinamani, xattr
series from Andreas, uaccess stuff from from me) and I'd prefer to
send those separately"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (39 commits)
proc: switch auxv to use of __mem_open()
hpfs: support FIEMAP
cifs: get rid of unused arguments of CIFSSMBWrite()
posix_acl: uapi header split
posix_acl: xattr representation cleanups
fs/aio.c: eliminate redundant loads in put_aio_ring_file
fs/internal.h: add const to ns_dentry_operations declaration
compat: remove compat_printk()
fs/buffer.c: make __getblk_slow() static
proc: unsigned file descriptors
fs/file: more unsigned file descriptors
fs: compat: remove redundant check of nr_segs
cachefiles: Fix attempt to read i_blocks after deleting file [ver #2]
cifs: don't use memcpy() to copy struct iov_iter
get rid of separate multipage fault-in primitives
fs: Avoid premature clearing of capabilities
fs: Give dentry to inode_change_ok() instead of inode
fuse: Propagate dentry down to inode_change_ok()
ceph: Propagate dentry down to inode_change_ok()
xfs: Propagate dentry down to inode_change_ok()
...
looking for duplicate ->iov_base makes sense only for
iovec-backed iterators; for kvec-backed ones it's pointless,
for bvec-backed ones it's pointless and broken on 32bit (we
walk through an array of struct bio_vec accessing them as if
they were struct iovec; works by accident on 64bit, but on
32bit it'll blow up) and for pipe-backed ones it's pointless
and ends up oopsing.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case. Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
After backporting commit ee44b4bc05 ("dlm: use sctp 1-to-1 API")
series to a kernel with an older workqueue which didn't use RCU yet, it
was noticed that we are freeing the workqueues in dlm_lowcomms_stop()
too early as free_conn() will try to access that memory for canceling
the queued works if any.
This issue was introduced by commit 0d737a8cfd as before it such
attempt to cancel the queued works wasn't performed, so the issue was
not present.
This patch fixes it by simply inverting the free order.
Cc: stable@vger.kernel.org
Fixes: 0d737a8cfd ("dlm: fix race while closing connections")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Merge updates from Andrew Morton:
- fsnotify updates
- ocfs2 updates
- all of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (127 commits)
console: don't prefer first registered if DT specifies stdout-path
cred: simpler, 1D supplementary groups
CREDITS: update Pavel's information, add GPG key, remove snail mail address
mailmap: add Johan Hovold
.gitattributes: set git diff driver for C source code files
uprobes: remove function declarations from arch/{mips,s390}
spelling.txt: "modeled" is spelt correctly
nmi_backtrace: generate one-line reports for idle cpus
arch/tile: adopt the new nmi_backtrace framework
nmi_backtrace: do a local dump_stack() instead of a self-NMI
nmi_backtrace: add more trigger_*_cpu_backtrace() methods
min/max: remove sparse warnings when they're nested
Documentation/filesystems/proc.txt: add more description for maps/smaps
mm, proc: fix region lost in /proc/self/smaps
proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self
proc: add LSM hook checks to /proc/<tid>/timerslack_ns
proc: relax /proc/<tid>/timerslack_ns capability requirements
meminfo: break apart a very long seq_printf with #ifdefs
seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char
proc: faster /proc/*/status
...
These inode operations are no longer used; remove them.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Current supplementary groups code can massively overallocate memory and
is implemented in a way so that access to individual gid is done via 2D
array.
If number of gids is <= 32, memory allocation is more or less tolerable
(140/148 bytes). But if it is not, code allocates full page (!)
regardless and, what's even more fun, doesn't reuse small 32-entry
array.
2D array means dependent shifts, loads and LEAs without possibility to
optimize them (gid is never known at compile time).
All of the above is unnecessary. Switch to the usual
trailing-zero-len-array scheme. Memory is allocated with
kmalloc/vmalloc() and only as much as needed. Accesses become simpler
(LEA 8(gi,idx,4) or even without displacement).
Maximum number of gids is 65536 which translates to 256KB+8 bytes. I
think kernel can handle such allocation.
On my usual desktop system with whole 9 (nine) aux groups, struct
group_info shrinks from 148 bytes to 44 bytes, yay!
Nice side effects:
- "gi->gid[i]" is shorter than "GROUP_AT(gi, i)", less typing,
- fix little mess in net/ipv4/ping.c
should have been using GROUP_AT macro but this point becomes moot,
- aux group allocation is persistent and should be accounted as such.
Link: http://lkml.kernel.org/r/20160817201927.GA2096@p183.telecom.by
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently, Redhat reported that nvml test suite failed on QEMU/KVM,
more detailed info please refer to:
https://bugzilla.redhat.com/show_bug.cgi?id=1365721
Actually, this bug is not only for NVDIMM/DAX but also for any other
file systems. This simple test case abstracted from nvml can easily
reproduce this bug in common environment:
-------------------------- testcase.c -----------------------------
int
is_pmem_proc(const void *addr, size_t len)
{
const char *caddr = addr;
FILE *fp;
if ((fp = fopen("/proc/self/smaps", "r")) == NULL) {
printf("!/proc/self/smaps");
return 0;
}
int retval = 0; /* assume false until proven otherwise */
char line[PROCMAXLEN]; /* for fgets() */
char *lo = NULL; /* beginning of current range in smaps file */
char *hi = NULL; /* end of current range in smaps file */
int needmm = 0; /* looking for mm flag for current range */
while (fgets(line, PROCMAXLEN, fp) != NULL) {
static const char vmflags[] = "VmFlags:";
static const char mm[] = " wr";
/* check for range line */
if (sscanf(line, "%p-%p", &lo, &hi) == 2) {
if (needmm) {
/* last range matched, but no mm flag found */
printf("never found mm flag.\n");
break;
} else if (caddr < lo) {
/* never found the range for caddr */
printf("#######no match for addr %p.\n", caddr);
break;
} else if (caddr < hi) {
/* start address is in this range */
size_t rangelen = (size_t)(hi - caddr);
/* remember that matching has started */
needmm = 1;
/* calculate remaining range to search for */
if (len > rangelen) {
len -= rangelen;
caddr += rangelen;
printf("matched %zu bytes in range "
"%p-%p, %zu left over.\n",
rangelen, lo, hi, len);
} else {
len = 0;
printf("matched all bytes in range "
"%p-%p.\n", lo, hi);
}
}
} else if (needmm && strncmp(line, vmflags,
sizeof(vmflags) - 1) == 0) {
if (strstr(&line[sizeof(vmflags) - 1], mm) != NULL) {
printf("mm flag found.\n");
if (len == 0) {
/* entire range matched */
retval = 1;
break;
}
needmm = 0; /* saw what was needed */
} else {
/* mm flag not set for some or all of range */
printf("range has no mm flag.\n");
break;
}
}
}
fclose(fp);
printf("returning %d.\n", retval);
return retval;
}
void *Addr;
size_t Size;
/*
* worker -- the work each thread performs
*/
static void *
worker(void *arg)
{
int *ret = (int *)arg;
*ret = is_pmem_proc(Addr, Size);
return NULL;
}
int main(int argc, char *argv[])
{
if (argc < 2 || argc > 3) {
printf("usage: %s file [env].\n", argv[0]);
return -1;
}
int fd = open(argv[1], O_RDWR);
struct stat stbuf;
fstat(fd, &stbuf);
Size = stbuf.st_size;
Addr = mmap(0, stbuf.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
close(fd);
pthread_t threads[NTHREAD];
int ret[NTHREAD];
/* kick off NTHREAD threads */
for (int i = 0; i < NTHREAD; i++)
pthread_create(&threads[i], NULL, worker, &ret[i]);
/* wait for all the threads to complete */
for (int i = 0; i < NTHREAD; i++)
pthread_join(threads[i], NULL);
/* verify that all the threads return the same value */
for (int i = 1; i < NTHREAD; i++) {
if (ret[0] != ret[i]) {
printf("Error i %d ret[0] = %d ret[i] = %d.\n", i,
ret[0], ret[i]);
}
}
printf("%d", ret[0]);
return 0;
}
It failed as some threads can not find the memory region in
"/proc/self/smaps" which is allocated in the main process
It is caused by proc fs which uses 'file->version' to indicate the VMA that
is the last one has already been handled by read() system call. When the
next read() issues, it uses the 'version' to find the VMA, then the next
VMA is what we want to handle, the related code is as follows:
if (last_addr) {
vma = find_vma(mm, last_addr);
if (vma && (vma = m_next_vma(priv, vma)))
return vma;
}
However, VMA will be lost if the last VMA is gone, e.g:
The process VMA list is A->B->C->D
CPU 0 CPU 1
read() system call
handle VMA B
version = B
return to userspace
unmap VMA B
issue read() again to continue to get
the region info
find_vma(version) will get VMA C
m_next_vma(C) will get VMA D
handle D
!!! VMA C is lost !!!
In order to fix this bug, we make 'file->version' indicate the end address
of the current VMA. m_start will then look up a vma which with vma_start
< last_vm_end and moves on to the next vma if we found the same or an
overlapping vma. This will guarantee that we will not miss an exclusive
vma but we can still miss one if the previous vma was shrunk. This is
acceptable because guaranteeing "never miss a vma" is simply not feasible.
User has to cope with some inconsistencies if the file is not read in one
go.
[mhocko@suse.com: changelog fixes]
Link: http://lkml.kernel.org/r/1475296958-27652-1-git-send-email-robert.hu@intel.com
Acked-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Robert Hu <robert.hu@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In changing from checking ptrace_may_access(p, PTRACE_MODE_ATTACH_FSCREDS)
to capable(CAP_SYS_NICE), I missed that ptrace_my_access succeeds when p
== current, but the CAP_SYS_NICE doesn't.
Thus while the previous commit was intended to loosen the needed
privileges to modify a processes timerslack, it needlessly restricted a
task modifying its own timerslack via the proc/<tid>/timerslack_ns
(which is permitted also via the PR_SET_TIMERSLACK method).
This patch corrects this by checking if p == current before checking the
CAP_SYS_NICE value.
This patch applies on top of my two previous patches currently in -mm
Link: http://lkml.kernel.org/r/1471906870-28624-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Colin Cross <ccross@android.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Elliott Hughes <enh@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As requested, this patch checks the existing LSM hooks
task_getscheduler/task_setscheduler when reading or modifying the task's
timerslack value.
Previous versions added new get/settimerslack LSM hooks, but since they
checked the same PROCESS__SET/GETSCHED values as existing hooks, it was
suggested we just use the existing ones.
Link: http://lkml.kernel.org/r/1469132667-17377-2-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Colin Cross <ccross@android.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Elliott Hughes <enh@google.com>
Cc: James Morris <jmorris@namei.org>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When an interface to allow a task to change another tasks timerslack was
first proposed, it was suggested that something greater then
CAP_SYS_NICE would be needed, as a task could be delayed further then
what normally could be done with nice adjustments.
So CAP_SYS_PTRACE was adopted instead for what became the
/proc/<tid>/timerslack_ns interface. However, for Android (where this
feature originates), giving the system_server CAP_SYS_PTRACE would allow
it to observe and modify all tasks memory. This is considered too high
a privilege level for only needing to change the timerslack.
After some discussion, it was realized that a CAP_SYS_NICE process can
set a task as SCHED_FIFO, so they could fork some spinning processes and
set them all SCHED_FIFO 99, in effect delaying all other tasks for an
infinite amount of time.
So as a CAP_SYS_NICE task can already cause trouble for other tasks,
using it as a required capability for accessing and modifying
/proc/<tid>/timerslack_ns seems sufficient.
Thus, this patch loosens the capability requirements to CAP_SYS_NICE and
removes CAP_SYS_PTRACE, simplifying some of the code flow as well.
This is technically an ABI change, but as the feature just landed in
4.6, I suspect no one is yet using it.
Link: http://lkml.kernel.org/r/1469132667-17377-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Nick Kralevich <nnk@google.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Colin Cross <ccross@android.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Elliott Hughes <enh@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use a specific routine to emit most lines so that the code is easier to
read and maintain.
akpm:
text data bss dec hex filename
2976 8 0 2984 ba8 fs/proc/meminfo.o before
2669 8 0 2677 a75 fs/proc/meminfo.o after
Link: http://lkml.kernel.org/r/8fce7fdef2ba081a4ef531594e97da8a9feebb58.1470810406.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow some seq_puts removals by taking a string instead of a single
char.
[akpm@linux-foundation.org: update vmstat_show(), per Joe]
Link: http://lkml.kernel.org/r/667e1cf3d436de91a5698170a1e98d882905e956.1470704995.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Joe Perches <joe@perches.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michael Kerrisk (man-pages)
Tomohiro Kusumi
Ian Kent
Vlastimil Babka
Darrick J. Wong
Guozhonghua
Linus Torvalds
Al Viro
Marcelo Ricardo Leitner
Andreas Gruenbacher
Alexey Dobriyan
Robert Ho
John Stultz
Joe Perches