With 2.6.37-rc1, I observe sys_ioprio_set not taking the RCU lock [1]
across access to the task credentials.
Inspecting the code in fs/ioprio.c, the tasklist_lock is held for read
across the __task_cred call, which is presumably sufficient to prevent
the task credentials becoming stale.
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
kernel/pid.c:419 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
1 lock held by start-stop-daem/2246:
#0: (tasklist_lock){.?.?..}, at: [<ffffffff811a2dfa>]
sys_ioprio_set+0x8a/0x400
stack backtrace:
Pid: 2246, comm: start-stop-daem Not tainted 2.6.37-rc1-330cd+ #2
Call Trace:
[<ffffffff8109f5f4>] lockdep_rcu_dereference+0xa4/0xc0
[<ffffffff81085651>] find_task_by_pid_ns+0x81/0x90
[<ffffffff8108567d>] find_task_by_vpid+0x1d/0x20
[<ffffffff811a3160>] sys_ioprio_set+0x3f0/0x400
[<ffffffff816efa79>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81003482>] system_call_fastpath+0x16/0x1b
Take the RCU lock for read across acquiring the pointer to the task
credentials and dereferencing it.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Fixed up by Jens to fix missing rcu_read_unlock() on mismatches.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Correct function being needlessly visible outside compilation unit
when the only users are internal.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Correct allocation flags type and function prototype for ANSI C compliance.
[airlied: whitespace fixed]
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Using a program like the following:
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main() {
id_t id;
siginfo_t infop;
pid_t res;
id = fork();
if (id == 0) { sleep(1); exit(0); }
kill(id, SIGSTOP);
alarm(1);
waitid(P_PID, id, &infop, WCONTINUED);
return 0;
}
to call waitid() on a stopped process results in access to the child task's
credentials without the RCU read lock being held - which may be replaced in the
meantime - eliciting the following warning:
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
kernel/exit.c:1460 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 1
2 locks held by waitid02/22252:
#0: (tasklist_lock){.?.?..}, at: [<ffffffff81061ce5>] do_wait+0xc5/0x310
#1: (&(&sighand->siglock)->rlock){-.-...}, at: [<ffffffff810611da>]
wait_consider_task+0x19a/0xbe0
stack backtrace:
Pid: 22252, comm: waitid02 Not tainted 2.6.35-323cd+ #3
Call Trace:
[<ffffffff81095da4>] lockdep_rcu_dereference+0xa4/0xc0
[<ffffffff81061b31>] wait_consider_task+0xaf1/0xbe0
[<ffffffff81061d15>] do_wait+0xf5/0x310
[<ffffffff810620b6>] sys_waitid+0x86/0x1f0
[<ffffffff8105fce0>] ? child_wait_callback+0x0/0x70
[<ffffffff81003282>] system_call_fastpath+0x16/0x1b
This is fixed by holding the RCU read lock in wait_task_continued() to ensure
that the task's current credentials aren't destroyed between us reading the
cred pointer and us reading the UID from those credentials.
Furthermore, protect wait_task_stopped() in the same way.
We don't need to keep holding the RCU read lock once we've read the UID from
the credentials as holding the RCU read lock doesn't stop the target task from
changing its creds under us - so the credentials may be outdated immediately
after we've read the pointer, lock or no lock.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix HDA beep frequency on IDT 92HD73xx and 92HD71Bxx codecs.
These codecs use the standard beep frequency calculation although the
datasheet says it's linear frequency.
Other IDT/STAC codecs might have the same problem. They should be
fixed individually later.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Don't print failure to detect Core i7 EDAC facilities to the console at
boot time, most often occurring on Core i7 desktops and laptops.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When booting 2.6.35-rc3 on a x86 system without an ERST ACPI table with
the 'quiet' option, we still observe an "ERST: Table is not found!"
warning.
Quiesce it to the same info log level as the other 'table not found'
warnings.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The task_group() function returns a pointer that must be protected
by either RCU, the ->alloc_lock, or the cgroup lock (see the
rcu_dereference_check() in task_subsys_state(), which is invoked by
task_group()). The wake_affine() function currently does none of these,
which means that a concurrent update would be within its rights to free
the structure returned by task_group(). Because wake_affine() uses this
structure only to compute load-balancing heuristics, there is no reason
to acquire either of the two locks.
Therefore, this commit introduces an RCU read-side critical section that
starts before the first call to task_group() and ends after the last use
of the "tg" pointer returned from task_group(). Thanks to Li Zefan for
pointing out the need to extend the RCU read-side critical section from
that proposed by the original patch.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
In commit e9fb7631eb ("cpu-hotplug: introduce cpu_notify(),
__cpu_notify(), cpu_notify_nofail()") the new helper functions access
cpu_chain. As a result, it shouldn't be marked __cpuinitdata (via
section mismatch warning).
Alternatively, the helper functions should be forced inline, or marked
__ref or __cpuinit. In the meantime, this patch silences the warning
the trivial way.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While investigating Intel i5 Arrandale GPU lockups with -rc4, I
noticed a lock imbalance.
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Add control of fan minimum turn-on output levels, decoupling it from the
fan turn-off output level. Add control of rate of change of fan output
level. These in turn allow lower turn-off rotor speed and smoother
transitions for better thermal and acoustic control authority. Add
support for constant fan speed and proportional-response operations modes.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: David Hubbard <david.c.hubbard@gmail.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
WARNING: arch/x86/mm/built-in.o(.text+0x3a1): Section mismatch in
reference from the function set_pte_phys() to the function
.init.text:spp_getpage()
The function set_pte_phys() references
the function __init spp_getpage().
This is often because set_pte_phys lacks a __init
annotation or the annotation of spp_getpage is wrong.
arch/x86/mm/init_64.c: In function 'early_memtest':
arch/x86/mm/init_64.c:520: warning: passing argument 2 of
'find_e820_area_size' from incompatible pointer type
Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Daniel J Blueman