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Even since a previous patch:
Fix race between CONFIG_DEBUG_SLABALLOC and modules
Sun, 27 Jun 2004 17:55:19 +0000 (17:55 +0000)
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit;h=92b3db26d31cf21b70e3c1eadc56c179506d8fbe
The function symbol_put_addr() will deadlock the kernel.
symbol_put_addr() would acquire modlist_lock, then while holding the lock call
two functions kernel_text_address() and module_text_address() which also try
to acquire the same lock. This deadlocks the kernel of course.
This patch changes symbol_put_addr() to not acquire the modlist_lock, it
doesn't need it since it never looks at the module list directly. Also, it
now uses core_kernel_text() instead of kernel_text_address(). The latter has
an additional check for addr inside a module, but we don't need to do that
since we call module_text_address() (the same function kernel_text_address
uses) ourselves.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Cc: Zwane Mwaikambo <zwane@fsmlabs.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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With "Paul E. McKenney" <paulmck@us.ibm.com>
Introduce rcu_needs_cpu() interface. This can be used to tell if there
will be a new rcu batch on a cpu soon by looking at the curlist pointer.
This can be used to avoid to enter a tickless idle state where the cpu
would miss that a new batch is ready when rcu_start_batch would be called
on a different cpu.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Eric Biederman points out that we can't take the task_lock while holding
tasklist_lock for writing, because another CPU that holds the task lock
might take an interrupt that then tries to take tasklist_lock for writing.
Which would be a nasty deadlock, with one CPU spinning forever in an
interrupt handler (although admittedly you need to really work at
triggering it ;)
Since the ptrace_attach() code is special and very unusual, just make it
be extra careful, and use trylock+repeat to avoid the possible deadlock.
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This holds the task lock (and, for ptrace_attach, the tasklist_lock)
over the actual attach event, which closes a race between attacking to a
thread that is either doing a PTRACE_TRACEME or getting de-threaded.
Thanks to Oleg Nesterov for reminding me about this, and Chris Wright
for noticing a lost return value in my first version.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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While testing the watch performance, I noticed that selinux_task_ctxid()
was creeping into the results more than it should. Investigation showed
that the function call was being called whether it was needed or not. The
below patch fixes this.
Signed-off-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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1) The audit_ipc_perms() function has been split into two different
functions:
- audit_ipc_obj()
- audit_ipc_set_perm()
There's a key shift here... The audit_ipc_obj() collects the uid, gid,
mode, and SElinux context label of the current ipc object. This
audit_ipc_obj() hook is now found in several places. Most notably, it
is hooked in ipcperms(), which is called in various places around the
ipc code permforming a MAC check. Additionally there are several places
where *checkid() is used to validate that an operation is being
performed on a valid object while not necessarily having a nearby
ipcperms() call. In these locations, audit_ipc_obj() is called to
ensure that the information is captured by the audit system.
The audit_set_new_perm() function is called any time the permissions on
the ipc object changes. In this case, the NEW permissions are recorded
(and note that an audit_ipc_obj() call exists just a few lines before
each instance).
2) Support for an AUDIT_IPC_SET_PERM audit message type. This allows
for separate auxiliary audit records for normal operations on an IPC
object and permissions changes. Note that the same struct
audit_aux_data_ipcctl is used and populated, however there are separate
audit_log_format statements based on the type of the message. Finally,
the AUDIT_IPC block of code in audit_free_aux() was extended to handle
aux messages of this new type. No more mem leaks I hope ;-)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Hi,
The patch below builds upon the patch sent earlier and adds subject label to
all audit events generated via the netlink interface. It also cleans up a few
other minor things.
Signed-off-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The below patch should be applied after the inode and ipc sid patches.
This patch is a reworking of Tim's patch that has been updated to match
the inode and ipc patches since its similar.
[updated:
> Stephen Smalley also wanted to change a variable from isec to tsec in the
> user sid patch. ]
Signed-off-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Hi,
The patch below converts IPC auditing to collect sid's and convert to context
string only if it needs to output an audit record. This patch depends on the
inode audit change patch already being applied.
Signed-off-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Previously, we were gathering the context instead of the sid. Now in this patch,
we gather just the sid and convert to context only if an audit event is being
output.
This patch brings the performance hit from 146% down to 23%
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This patch provides the ability to filter audit messages based on the
elements of the process' SELinux context (user, role, type, mls sensitivity,
and mls clearance). It uses the new interfaces from selinux to opaquely
store information related to the selinux context and to filter based on that
information. It also uses the callback mechanism provided by selinux to
refresh the information when a new policy is loaded.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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audit_syscall_exit()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... it's always current, and that's a good thing - allows simpler locking.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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now we can do that - all callers are process-synchronous and do not hold
any locks.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Don't assume that audit_log_exit() et.al. are called for the context of
current; pass task explictly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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- Add new SA_PROBEIRQ which suppresses the new sharing-mismatch warning.
Some drivers like to use request_irq() to find an unused interrupt slot.
- Use it in i82365.c
- Kill unused SA_PROBE.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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There's an off-by-1 in kernel/power/main.c:state_store() ... if your
kernel just happens to have some non-zero data at pm_states[PM_SUSPEND_MAX]
(i.e. one past the end of the array) then it'll let you write anything you
want to /sys/power/state and in response the box will enter S5.
Signed-off-by: dean gaudet <dean@arctic.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Few of the notifier_chain_register() callers use __init in the definition
of notifier_call. It is incorrect as the function definition should be
available after the initializations (they do not unregister them during
initializations).
This patch fixes all such usages to _not_ have the notifier_call __init
section.
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Few of the notifier_chain_register() callers use __devinitdata in the
definition of notifier_block data structure. It is incorrect as the
data structure should be available after the initializations (they do
not unregister them during initializations).
This was leading to an oops when notifier_chain_register() call is
invoked for those callback chains after initialization.
This patch fixes all such usages to _not_ have the notifier_block data
structure in the init data section.
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* 'for-linus' of git://brick.kernel.dk/data/git/linux-2.6-block:
[PATCH] block/elevator.c: remove unused exports
[PATCH] splice: fix smaller sized splice reads
[PATCH] Don't inherit ->splice_pipe across forks
[patch] cleanup: use blk_queue_stopped
[PATCH] Document online io scheduler switching
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In cases where a struct kretprobe's *_handler fields are non-NULL, it is
possible to cause a system crash, due to the possibility of calls ending up
in zombie functions. Documentation clearly states that unused *_handlers
should be set to NULL, but kprobe users sometimes fail to do so.
Fix it by setting the non-relevant fields of the struct kretprobe to NULL.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It's really task private, so clear that field on fork after copying
task structure.
Signed-off-by: Jens Axboe <axboe@suse.de>
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Those also break userland regs like following.
00000000 <sys_chown16>:
0: 0f b7 44 24 0c movzwl 0xc(%esp),%eax
5: 83 ca ff or $0xffffffff,%edx
8: 0f b7 4c 24 08 movzwl 0x8(%esp),%ecx
d: 66 83 f8 ff cmp $0xffffffff,%ax
11: 0f 44 c2 cmove %edx,%eax
14: 66 83 f9 ff cmp $0xffffffff,%cx
18: 0f 45 d1 cmovne %ecx,%edx
1b: 89 44 24 0c mov %eax,0xc(%esp)
1f: 89 54 24 08 mov %edx,0x8(%esp)
23: e9 fc ff ff ff jmp 24 <sys_chown16+0x24>
where the tailcall at the end overwrites the incoming stack-frame.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
[ I would _really_ like to have a way to tell gcc about calling
conventions. The "prevent_tail_call()" macro is pretty ugly ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The function free_pagedir() used by swsusp for freeing its internal data
structures clears the PG_nosave and PG_nosave_free flags for each page
being freed.
However, during resume PG_nosave_free set means that the page in
question is "unsafe" (ie. it will be overwritten in the process of
restoring the saved system state from the image), so it should not be
used for the image data.
Therefore free_pagedir() should not clear PG_nosave_free if it's called
during resume (otherwise "unsafe" pages freed by it may be used for
storing the image data and the data may get corrupted later on).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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While we can currently walk through thread groups, process groups, and
sessions with just the rcu_read_lock, this opens the door to walking the
entire task list.
We already have all of the other RCU guarantees so there is no cost in
doing this, this should be enough so that proc can stop taking the
tasklist lock during readdir.
prev_task was killed because it has no users, and using it will miss new
tasks when doing an rcu traversal.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Somehow in the midst of dotting i's and crossing t's during
the merge up to rc1 we wound up keeping __put_task_struct_cb
when it should have been killed as it no longer has any users.
Sorry I probably should have caught this while it was
still in the -mm tree.
Having the old code there gets confusing when reading
through the code and trying to understand what is
happening.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Since the last user is removed in -mm, we can now remove this long deprecated
function.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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This reverts most of commit 30e0fca6c1d7d26f3f2daa4dd2b12c51dadc778a.
It broke the case of non-leader MT exec when ptraced.
I think the bug it was intended to fix was already addressed by commit
788e05a67c343fa22f2ae1d3ca264e7f15c25eaf.
Signed-off-by: Roland McGrath <roland@redhat.com>
Acked-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Commit e56d090310d7625ecb43a1eeebd479f04affb48b
[PATCH] RCU signal handling
made this BUG_ON() unsafe. This code runs under ->siglock,
while switch_exec_pids() takes tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* 'splice' of git://brick.kernel.dk/data/git/linux-2.6-block:
[PATCH] vfs: add splice_write and splice_read to documentation
[PATCH] Remove sys_ prefix of new syscalls from __NR_sys_*
[PATCH] splice: warning fix
[PATCH] another round of fs/pipe.c cleanups
[PATCH] splice: comment styles
[PATCH] splice: add Ingo as addition copyright holder
[PATCH] splice: unlikely() optimizations
[PATCH] splice: speedups and optimizations
[PATCH] pipe.c/fifo.c code cleanups
[PATCH] get rid of the PIPE_*() macros
[PATCH] splice: speedup __generic_file_splice_read
[PATCH] splice: add direct fd <-> fd splicing support
[PATCH] splice: add optional input and output offsets
[PATCH] introduce a "kernel-internal pipe object" abstraction
[PATCH] splice: be smarter about calling do_page_cache_readahead()
[PATCH] splice: optimize the splice buffer mapping
[PATCH] splice: cleanup __generic_file_splice_read()
[PATCH] splice: only call wake_up_interruptible() when we really have to
[PATCH] splice: potential !page dereference
[PATCH] splice: mark the io page as accessed
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Add a cpu_relax() to the hand-coded spinwait in hrtimer_cancel().
Signed-off-by: Joe Korty <joe.korty@ccur.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Implement the scheduled unexport of panic_timeout.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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We need the boot CPU's tvec_bases[] entry to be initialised super-early in
boot, for early_serial_setup(). That runs within setup_arch(), before even
per-cpu areas are initialised.
The patch changes tvec_bases to use compile-time initialisation, and adds a
separate array `tvec_base_done' to keep track of which CPU has had its
tvec_bases[] entry initialised (because we can no longer use the zeroness of
that tvec_bases[] entry to determine whether it has been initialised).
Thanks to Eugene Surovegin <ebs@ebshome.net> for diagnosing this.
Cc: Eugene Surovegin <ebs@ebshome.net>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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up unneeded macros
For some architectures, a few syscalls are not linked in noMMU mode. In
that case, the MMU depending syscalls are needed to be defined as
'cond_syscall'. For example, ARM architecture selectively links sys_mlock
by the mode configuration.
In case of FRV, it has been managed by #ifdef CONFIG_MMU macro in
arch/frv/kernel/entry.S. However these conditional macros are just
duplicates if they were defined as cond_syscall. Compilation test is done
with FRV toolchains for both of MMU and noMMU mode.
Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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RT tasks are being awakened on the expired array when expired_starving() is
true, whereas they really should be excluded. Fix.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix a starvation problem that occurs when a stream of highly interactive tasks
delay an array switch for extended periods despite EXPIRED_STARVING(rq) being
true. AFAIKT, the only choice is to enqueue awakening tasks on the expired
array in this case.
Without this patch, it can be nearly impossible to remotely login to a busy
server, and interactive shell commands can starve for minutes.
Also, convert the EXPIRED_STARVING macro into an inline function which humans
can understand.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It's more efficient for sendfile() emulation. Basically we cache an
internal private pipe and just use that as the intermediate area for
pages. Direct splicing is not available from sys_splice(), it is only
meant to be used for sendfile() emulation.
Additional patch from Ingo Molnar to avoid the PIPE_BUFFERS loop at
exit for the normal fast path.
Signed-off-by: Jens Axboe <axboe@suse.de>
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If the HPET timer is enabled, the clock can drift by ~3 seconds a day.
This is due to the HPET timer not being initialized with the correct
setting (still using PIT count).
If HZ changes, this drift can become even more pronounced.
HPET patch initializes tick_nsec with correct tick_nsec settings for
HPET timer.
Vojtech comments:
"It's not entirely correct (it assumes the HPET ticks totally
exactly), but it's significantly better than assuming the PIT error
there."
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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I was grepping through the code and some `grep ganularity -R .` didn't
catch what I thought. Then looking closer I saw the term "granuality"
used in only four places (in comments) and granularity in many more
places describing the same idea. Some other facts:
dictionary.com does not know such a word
define:granuality on google is not found (and pages for granuality are
mostly related to patches to the kernel)
it has not been discussed as a term on LKML, AFAICS (=Can Search)
To be consistent, I think granularity should be used everywhere.
Signed-off-by: Kalin KOZHUHAROV <kalin@thinrope.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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this changes if() BUG(); constructs to BUG_ON() which is
cleaner, contains unlikely() and can better optimized away.
Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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The note that SOFTWARE_SUSPEND doesn't need APM is helpful, but nowadays
the information that it doesn't need ACPI, too, is even more helpful.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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Wrong error path in dup_fd() - it should return NULL on error,
not an address of already freed memory :/
Triggered by OpenVZ stress test suite.
What is interesting is that it was causing different oopses in RCU like
below:
Call Trace:
[<c013492c>] rcu_do_batch+0x2c/0x80
[<c0134bdd>] rcu_process_callbacks+0x3d/0x70
[<c0126cf3>] tasklet_action+0x73/0xe0
[<c01269aa>] __do_softirq+0x10a/0x130
[<c01058ff>] do_softirq+0x4f/0x60
=======================
[<c0113817>] smp_apic_timer_interrupt+0x77/0x110
[<c0103b54>] apic_timer_interrupt+0x1c/0x24
Code: Bad EIP value.
<0>Kernel panic - not syncing: Fatal exception in interrupt
Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Dmitry Mishin <dim@openvz.org>
Signed-Off-By: Kirill Korotaev <dev@openvz.org>
Signed-Off-By: Linus Torvalds <torvalds@osdl.org>
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Simplifies the code, reduces the need for 4 pid hash tables, and makes the
code more capable.
In the discussions I had with Oleg it was felt that to a large extent the
cleanup itself justified the work. With struct pid being dynamically
allocated meant we could create the hash table entry when the pid was
allocated and free the hash table entry when the pid was freed. Instead of
playing with the hash lists when ever a process would attach or detach to a
process.
For myself the fact that it gave what my previous task_ref patch gave for free
with simpler code was a big win. The problem is that if you hold a reference
to struct task_struct you lock in 10K of low memory. If you do that in a user
controllable way like /proc does, with an unprivileged but hostile user space
application with typical resource limits of 1000 fds and 100 processes I can
trigger the OOM killer by consuming all of low memory with task structs, on a
machine wight 1GB of low memory.
If I instead hold a reference to struct pid which holds a pointer to my
task_struct, I don't suffer from that problem because struct pid is 2 orders
of magnitude smaller. In fact struct pid is small enough that most other
kernel data structures dwarf it, so simply limiting the number of referring
data structures is enough to prevent exhaustion of low memory.
This splits the current struct pid into two structures, struct pid and struct
pid_link, and reduces our number of hash tables from PIDTYPE_MAX to just one.
struct pid_link is the per process linkage into the hash tables and lives in
struct task_struct. struct pid is given an indepedent lifetime, and holds
pointers to each of the pid types.
The independent life of struct pid simplifies attach_pid, and detach_pid,
because we are always manipulating the list of pids and not the hash table.
In addition in giving struct pid an indpendent life it makes the concept much
more powerful.
Kernel data structures can now embed a struct pid * instead of a pid_t and
not suffer from pid wrap around problems or from keeping unnecessarily
large amounts of memory allocated.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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A big problem with rcu protected data structures that are also reference
counted is that you must jump through several hoops to increase the reference
count. I think someone finally implemented atomic_inc_not_zero(&count) to
automate the common case. Unfortunately this means you must special case the
rcu access case.
When data structures are only visible via rcu in a manner that is not
determined by the reference count on the object (i.e. tasks are visible until
their zombies are reaped) there is a much simpler technique we can employ.
Simply delaying the decrement of the reference count until the rcu interval is
over.
What that means is that the proc code that looks up a task and later
wants to sleep can now do:
rcu_read_lock();
task = find_task_by_pid(some_pid);
if (task) {
get_task_struct(task);
}
rcu_read_unlock();
The effect on the rest of the kernel is that put_task_struct becomes cheaper
and immediate, and in the case where the task has been reaped it frees the
task immediate instead of unnecessarily waiting an until the rcu interval is
over.
Cleanup of task_struct does not happen when its reference count drops to
zero, instead cleanup happens when release_task is called. Tasks can only
be looked up via rcu before release_task is called. All rcu protected
members of task_struct are freed by release_task.
Therefore we can move call_rcu from put_task_struct into release_task. And
we can modify release_task to not immediately release the reference count
but instead have it call put_task_struct from the function it gives to
call_rcu.
The end result:
- get_task_struct is safe in an rcu context where we have just looked
up the task.
- put_task_struct() simplifies into its old pre rcu self.
This reorganization also makes put_task_struct uncallable from modules as
it is not exported but it does not appear to be called from any modules so
this should not be an issue, and is trivially fixed.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This just got nuked in mainline. Bring it back because Eric's patches use it.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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