Commit Graph

29 Commits

Author SHA1 Message Date
Jens Axboe
3b7cb74547 block: move __get_task_ioprio() into header file
We call this once per IO, which can be millions of times per second.
Since nobody really uses io priorities, or at least it isn't very
common, this is all wasted time and can amount to as much as 3% of
the total kernel time.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-08 12:27:39 -07:00
Damien Le Moal
01584c1e23 scsi: block: Improve ioprio value validity checks
The introduction of the macro IOPRIO_PRIO_LEVEL() in commit eca2040972
("scsi: block: ioprio: Clean up interface definition") results in an
iopriority level to always be masked using the macro IOPRIO_LEVEL_MASK, and
thus to the kernel always seeing an acceptable value for an I/O priority
level when checked in ioprio_check_cap().  Before this patch, this function
would return an error for some (but not all) invalid values for a level
valid range of [0..7].

Restore and improve the detection of invalid priority levels by introducing
the inline function ioprio_value() to check an ioprio class, level and hint
value before combining these fields into a single value to be used with
ioprio_set() or AIOs. If an invalid value for the class, level or hint of
an ioprio is detected, ioprio_value() returns an ioprio using the class
IOPRIO_CLASS_INVALID, indicating an invalid value and causing
ioprio_check_cap() to return -EINVAL.

Fixes: 6c91325722 ("scsi: block: Introduce ioprio hints")
Fixes: eca2040972 ("scsi: block: ioprio: Clean up interface definition")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230608095556.124001-1-dlemoal@kernel.org
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2023-06-16 12:04:30 -04:00
Damien Le Moal
eca2040972 scsi: block: ioprio: Clean up interface definition
The I/O priority user interface defines the 16-bits ioprio values as the
combination of the upper 3-bits for an I/O priority class and the lower
13-bits as priority data. However, the kernel only uses the lower 3-bits of
the priority data to define priority levels for the RT and BE priority
classes. The data part of an ioprio value is completely ignored for the
IDLE and NONE classes. This is enforced by checks done in
ioprio_check_cap(), which is called for all paths that allow defining an
I/O priority for I/Os: the per-context ioprio_set() system call, aio
interface and io_uring interface.

Clarify this fact in the uapi ioprio.h header file and introduce the
IOPRIO_PRIO_LEVEL_MASK and IOPRIO_PRIO_LEVEL() macros for users to define
and get priority levels in an ioprio value. The coarser macro
IOPRIO_PRIO_DATA() is retained for backward compatibility with old
applications already using it. There is no functional change introduced
with this.

In-kernel users of the IOPRIO_PRIO_DATA() macro which are explicitly
handling I/O priority data as a priority level are modified to use the new
IOPRIO_PRIO_LEVEL() macro without any functional change. Since f2fs is the
only user of this macro not explicitly using that value as a priority
level, it is left unchanged.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Link: https://lore.kernel.org/r/20230511011356.227789-2-nks@flawful.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2023-05-22 17:05:18 -04:00
Jan Kara
4b838d9ee9 block: Fix handling of tasks without ioprio in ioprio_get(2)
ioprio_get(2) can be asked to return the best IO priority from several
tasks (IOPRIO_WHO_PGRP, IOPRIO_WHO_USER). Currently the call treats
tasks without set IO priority as having priority
IOPRIO_CLASS_BE/IOPRIO_BE_NORM however this does not really reflect the
IO priority the task will get (which depends on task's nice value).

Fix the code to use the real IO priority task's IO will use. We have to
modify code for ioprio_get(IOPRIO_WHO_PROCESS) to keep returning
IOPRIO_CLASS_NONE priority for tasks without set IO priority as a
special case to maintain userspace visible API.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220623074840.5960-5-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-27 06:29:12 -06:00
Jan Kara
fc25545e17 block: Make ioprio_best() static
Nobody outside of block/ioprio.c uses it.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220623074840.5960-4-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-27 06:29:12 -06:00
Jan Kara
893e5d32d5 block: Generalize get_current_ioprio() for any task
get_current_ioprio() operates only on current task. We will need the
same functionality for other tasks as well. Generalize
get_current_ioprio() for that and also move the bulk out of the header
file because it is large enough.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220623074840.5960-3-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-27 06:29:12 -06:00
Jan Kara
e589f46445 block: fix default IO priority handling again
Commit e70344c059 ("block: fix default IO priority handling")
introduced an inconsistency in get_current_ioprio() that tasks without
IO context return IOPRIO_DEFAULT priority while tasks with freshly
allocated IO context will return 0 (IOPRIO_CLASS_NONE/0) IO priority.
Tasks without IO context used to be rare before 5a9d041ba2 ("block:
move io_context creation into where it's needed") but after this commit
they became common because now only BFQ IO scheduler setups task's IO
context. Similar inconsistency is there for get_task_ioprio() so this
inconsistency is now exposed to userspace and userspace will see
different IO priority for tasks operating on devices with BFQ compared
to devices without BFQ. Furthemore the changes done by commit
e70344c059 change the behavior when no IO priority is set for BFQ IO
scheduler which is also documented in ioprio_set(2) manpage:

"If no I/O scheduler has been set for a thread, then by default the I/O
priority will follow the CPU nice value (setpriority(2)).  In Linux
kernels before version 2.6.24, once an I/O priority had been set using
ioprio_set(), there was no way to reset the I/O scheduling behavior to
the default. Since Linux 2.6.24, specifying ioprio as 0 can be used to
reset to the default I/O scheduling behavior."

So make sure we default to IOPRIO_CLASS_NONE as used to be the case
before commit e70344c059. Also cleanup alloc_io_context() to
explicitely set this IO priority for the allocated IO context to avoid
future surprises. Note that we tweak ioprio_best() to maintain
ioprio_get(2) behavior and make this commit easily backportable.

CC: stable@vger.kernel.org
Fixes: e70344c059 ("block: fix default IO priority handling")
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220623074840.5960-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-06-27 06:29:12 -06:00
Linus Torvalds
d3c8108035 for-5.17/block-2022-01-11
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Merge tag 'for-5.17/block-2022-01-11' of git://git.kernel.dk/linux-block

Pull block updates from Jens Axboe:

 - Unify where the struct request handling code is located in the blk-mq
   code (Christoph)

 - Header cleanups (Christoph)

 - Clean up the io_context handling code (Christoph, me)

 - Get rid of ->rq_disk in struct request (Christoph)

 - Error handling fix for add_disk() (Christoph)

 - request allocation cleanusp (Christoph)

 - Documentation updates (Eric, Matthew)

 - Remove trivial crypto unregister helper (Eric)

 - Reduce shared tag overhead (John)

 - Reduce poll_stats memory overhead (me)

 - Known indirect function call for dio (me)

 - Use atomic references for struct request (me)

 - Support request list issue for block and NVMe (me)

 - Improve queue dispatch pinning (Ming)

 - Improve the direct list issue code (Keith)

 - BFQ improvements (Jan)

 - Direct completion helper and use it in mmc block (Sebastian)

 - Use raw spinlock for the blktrace code (Wander)

 - fsync error handling fix (Ye)

 - Various fixes and cleanups (Lukas, Randy, Yang, Tetsuo, Ming, me)

* tag 'for-5.17/block-2022-01-11' of git://git.kernel.dk/linux-block: (132 commits)
  MAINTAINERS: add entries for block layer documentation
  docs: block: remove queue-sysfs.rst
  docs: sysfs-block: document virt_boundary_mask
  docs: sysfs-block: document stable_writes
  docs: sysfs-block: fill in missing documentation from queue-sysfs.rst
  docs: sysfs-block: add contact for nomerges
  docs: sysfs-block: sort alphabetically
  docs: sysfs-block: move to stable directory
  block: don't protect submit_bio_checks by q_usage_counter
  block: fix old-style declaration
  nvme-pci: fix queue_rqs list splitting
  block: introduce rq_list_move
  block: introduce rq_list_for_each_safe macro
  block: move rq_list macros to blk-mq.h
  block: drop needless assignment in set_task_ioprio()
  block: remove unnecessary trailing '\'
  bio.h: fix kernel-doc warnings
  block: check minor range in device_add_disk()
  block: use "unsigned long" for blk_validate_block_size().
  block: fix error unwinding in device_add_disk
  ...
2022-01-12 10:26:52 -08:00
Christoph Hellwig
a411cd3cfd block: move set_task_ioprio to blk-ioc.c
Keep set_task_ioprio with the other low-level code that accesses the
io_context structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211209063131.18537-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-16 10:59:01 -07:00
Davidlohr Bueso
e6a59aac8a block: fix ioprio_get(IOPRIO_WHO_PGRP) vs setuid(2)
do_each_pid_thread(PIDTYPE_PGID) can race with a concurrent
change_pid(PIDTYPE_PGID) that can move the task from one hlist
to another while iterating. Serialize ioprio_get to take
the tasklist_lock in this case, just like it's set counterpart.

Fixes: d69b78ba1d (ioprio: grab rcu_read_lock in sys_ioprio_{set,get}())
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20211210182058.43417-1-dave@stgolabs.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-12-10 11:26:07 -07:00
Alistair Delva
94c4b4fd25 block: Check ADMIN before NICE for IOPRIO_CLASS_RT
Booting to Android userspace on 5.14 or newer triggers the following
SELinux denial:

avc: denied { sys_nice } for comm="init" capability=23
     scontext=u:r:init:s0 tcontext=u:r:init:s0 tclass=capability
     permissive=0

Init is PID 0 running as root, so it already has CAP_SYS_ADMIN. For
better compatibility with older SEPolicy, check ADMIN before NICE.

Fixes: 9d3a39a5f1 ("block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE")
Signed-off-by: Alistair Delva <adelva@google.com>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: selinux@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: kernel-team@android.com
Cc: stable@vger.kernel.org # v5.14+
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Link: https://lore.kernel.org/r/20211115181655.3608659-1-adelva@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-15 14:28:59 -07:00
Damien Le Moal
e70344c059 block: fix default IO priority handling
The default IO priority is the best effort (BE) class with the
normal priority level IOPRIO_NORM (4). However, get_task_ioprio()
returns IOPRIO_CLASS_NONE/IOPRIO_NORM as the default priority and
get_current_ioprio() returns IOPRIO_CLASS_NONE/0. Let's be consistent
with the defined default and have both of these functions return the
default priority IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM) when
the user did not define another default IO priority for the task.

In include/uapi/linux/ioprio.h, introduce the IOPRIO_BE_NORM macro as
an alias to IOPRIO_NORM to clarify that this default level applies to
the BE priotity class. In include/linux/ioprio.h, define the macro
IOPRIO_DEFAULT as IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_BE_NORM)
and use this new macro when setting a priority to the default.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Link: https://lore.kernel.org/r/20210811033702.368488-7-damien.lemoal@wdc.com
[axboe: drop unnecessary lightnvm change]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-18 07:23:15 -06:00
Damien Le Moal
202bc942c5 block: Introduce IOPRIO_NR_LEVELS
The BFQ scheduler and ioprio_check_cap() both assume that the RT
priority class (IOPRIO_CLASS_RT) can have up to 8 different priority
levels, similarly to the BE class (IOPRIO_CLASS_iBE). This is
controlled using the IOPRIO_BE_NR macro , which is badly named as the
number of levels also applies to the RT class.

Introduce the class independent IOPRIO_NR_LEVELS macro, defined to 8,
to make things clear. Keep the old IOPRIO_BE_NR macro definition as an
alias for IOPRIO_NR_LEVELS.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Link: https://lore.kernel.org/r/20210811033702.368488-6-damien.lemoal@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-18 07:21:12 -06:00
Peter Zijlstra
40c7fd3fdf block: Fix sys_ioprio_set(.which=IOPRIO_WHO_PGRP) task iteration
do_each_pid_thread() { } while_each_pid_thread() is a double loop and
thus break doesn't work as expected. Also, it should be used under
tasklist_lock because otherwise we can race against change_pid() for
PGID/SID.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/YG7Q5C4Rb5dx5GFx@hirez.programming.kicks-ass.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-08 13:43:53 -06:00
Khazhismel Kumykov
9d3a39a5f1 block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE
CAP_SYS_ADMIN is too broad, and ionice fits into CAP_SYS_NICE's grouping.

Retain CAP_SYS_ADMIN permission for backwards compatibility.

Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-01 19:38:33 -06:00
Gustavo A. R. Silva
df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Mauro Carvalho Chehab
898bd37a92 docs: block: convert to ReST
Rename the block documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-15 09:20:27 -03:00
Christoph Hellwig
3dcf60bcb6 block: add SPDX tags to block layer files missing licensing information
Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 16:12:03 -06:00
Adam Manzanares
aa43457799 block: add ioprio_check_cap function
Aio per command iopriority support introduces a second interface between
userland and the kernel capable of passing iopriority. The aio interface also
needs the ability to verify that the submitting context has sufficient
privileges to submit IOPRIO_RT commands. This patch creates the
ioprio_check_cap function to be used by the ioprio_set system call and also by
the aio interface.

Signed-off-by: Adam Manzanares <adam.manzanares@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-05-31 10:50:54 -04:00
Bart Van Assche
e29387ebd8 block: Add fallthrough markers to switch statements
This patch suppresses gcc 7 warnings about falling through in switch
statements when building with W=1. From the gcc documentation: The
-Wimplicit-fallthrough=3 warning is enabled by -Wextra. See also
https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gcc/Warning-Options.html.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-21 11:46:07 -06:00
Bart Van Assche
9a87182c4b block: Optimize ioprio_best()
Since ioprio_best() translates IOPRIO_CLASS_NONE into IOPRIO_CLASS_BE
and since lower numerical priority values represent a higher priority
a simple numerical comparison is sufficient.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Adam Manzanares <adam.manzanares@wdc.com>
Tested-by: Adam Manzanares <adam.manzanares@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-19 17:38:36 -06:00
Ingo Molnar
f719ff9bce sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>
But first update the code that uses these facilities with the
new header.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:38 +01:00
Ingo Molnar
5b825c3af1 sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.

Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:31 +01:00
Ingo Molnar
8703e8a465 sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h>
We are going to split <linux/sched/user.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/user.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:29 +01:00
Tetsuo Handa
612dafabb6 block: use for_each_thread() in sys_ioprio_set()/sys_ioprio_get()
IOPRIO_WHO_USER case in sys_ioprio_set()/sys_ioprio_get() are using
while_each_thread(), which is unsafe under RCU lock according to commit
0c740d0afc ("introduce for_each_thread() to replace the buggy
while_each_thread()").  Use for_each_thread() (via
for_each_process_thread()) which is safe under RCU lock.

Link: http://lkml.kernel.org/r/201702011947.DBD56740.OMVHOLOtSJFFFQ@I-love.SAKURA.ne.jp
Link: http://lkml.kernel.org/r/1486041779-4401-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-22 16:41:27 -08:00
Omar Sandoval
8ba8682107 block: fix use-after-free in sys_ioprio_get()
get_task_ioprio() accesses the task->io_context without holding the task
lock and thus can race with exit_io_context(), leading to a
use-after-free. The reproducer below hits this within a few seconds on
my 4-core QEMU VM:

#define _GNU_SOURCE
#include <assert.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/wait.h>

int main(int argc, char **argv)
{
	pid_t pid, child;
	long nproc, i;

	/* ioprio_set(IOPRIO_WHO_PROCESS, 0, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)); */
	syscall(SYS_ioprio_set, 1, 0, 0x6000);

	nproc = sysconf(_SC_NPROCESSORS_ONLN);

	for (i = 0; i < nproc; i++) {
		pid = fork();
		assert(pid != -1);
		if (pid == 0) {
			for (;;) {
				pid = fork();
				assert(pid != -1);
				if (pid == 0) {
					_exit(0);
				} else {
					child = wait(NULL);
					assert(child == pid);
				}
			}
		}

		pid = fork();
		assert(pid != -1);
		if (pid == 0) {
			for (;;) {
				/* ioprio_get(IOPRIO_WHO_PGRP, 0); */
				syscall(SYS_ioprio_get, 2, 0);
			}
		}
	}

	for (;;) {
		/* ioprio_get(IOPRIO_WHO_PGRP, 0); */
		syscall(SYS_ioprio_get, 2, 0);
	}

	return 0;
}

This gets us KASAN dumps like this:

[   35.526914] ==================================================================
[   35.530009] BUG: KASAN: out-of-bounds in get_task_ioprio+0x7b/0x90 at addr ffff880066f34e6c
[   35.530009] Read of size 2 by task ioprio-gpf/363
[   35.530009] =============================================================================
[   35.530009] BUG blkdev_ioc (Not tainted): kasan: bad access detected
[   35.530009] -----------------------------------------------------------------------------

[   35.530009] Disabling lock debugging due to kernel taint
[   35.530009] INFO: Allocated in create_task_io_context+0x2b/0x370 age=0 cpu=0 pid=360
[   35.530009] 	___slab_alloc+0x55d/0x5a0
[   35.530009] 	__slab_alloc.isra.20+0x2b/0x40
[   35.530009] 	kmem_cache_alloc_node+0x84/0x200
[   35.530009] 	create_task_io_context+0x2b/0x370
[   35.530009] 	get_task_io_context+0x92/0xb0
[   35.530009] 	copy_process.part.8+0x5029/0x5660
[   35.530009] 	_do_fork+0x155/0x7e0
[   35.530009] 	SyS_clone+0x19/0x20
[   35.530009] 	do_syscall_64+0x195/0x3a0
[   35.530009] 	return_from_SYSCALL_64+0x0/0x6a
[   35.530009] INFO: Freed in put_io_context+0xe7/0x120 age=0 cpu=0 pid=1060
[   35.530009] 	__slab_free+0x27b/0x3d0
[   35.530009] 	kmem_cache_free+0x1fb/0x220
[   35.530009] 	put_io_context+0xe7/0x120
[   35.530009] 	put_io_context_active+0x238/0x380
[   35.530009] 	exit_io_context+0x66/0x80
[   35.530009] 	do_exit+0x158e/0x2b90
[   35.530009] 	do_group_exit+0xe5/0x2b0
[   35.530009] 	SyS_exit_group+0x1d/0x20
[   35.530009] 	entry_SYSCALL_64_fastpath+0x1a/0xa4
[   35.530009] INFO: Slab 0xffffea00019bcd00 objects=20 used=4 fp=0xffff880066f34ff0 flags=0x1fffe0000004080
[   35.530009] INFO: Object 0xffff880066f34e58 @offset=3672 fp=0x0000000000000001
[   35.530009] ==================================================================

Fix it by grabbing the task lock while we poke at the io_context.

Cc: stable@vger.kernel.org
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-01 08:39:24 -06:00
Ben Segall
8639b46139 pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode
setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of
the current pid namespace.  This is in contrast to both the other modes of
setpriority and the example of kill(-1).  Fix this.  getpriority and
ioprio have the same failure mode, fix them too.

Eric said:

: After some more thinking about it this patch sounds justifiable.
:
: My goal with namespaces is not to build perfect isolation mechanisms
: as that can get into ill defined territory, but to build well defined
: mechanisms.  And to handle the corner cases so you can use only
: a single namespace with well defined results.
:
: In this case you have found the two interfaces I am aware of that
: identify processes by uid instead of by pid.  Which quite frankly is
: weird.  Unfortunately the weird unexpected cases are hard to handle
: in the usual way.
:
: I was hoping for a little more information.  Changes like this one we
: have to be careful of because someone might be depending on the current
: behavior.  I don't think they are and I do think this make sense as part
: of the pid namespace.

Signed-off-by: Ben Segall <bsegall@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ambrose Feinstein <ambrose@google.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
Jan Kara
ece9c72acc block: Fix computation of merged request priority
Priority of a merged request is computed by ioprio_best(). If one of the
requests has undefined priority (IOPRIO_CLASS_NONE) and another request
has priority from IOPRIO_CLASS_BE, the function will return the
undefined priority which is wrong. Fix the function to properly return
priority of a request with the defined priority.

Fixes: d58cdfb89c
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2014-10-31 08:30:43 -06:00
Jens Axboe
2667bcbbd5 block: move ioprio.c from fs/ to block/
Like commit f9c78b2b, move this block related file outside
of fs/ and into the core block directory, block/.

Signed-off-by: Jens Axboe <axboe@fb.com>
2014-05-19 11:02:18 -06:00