When debugging a recent lockup bug i found various deficiencies
in how our current lockup detection helpers work:
- SysRq-L is not very efficient as it uses a workqueue, hence
it cannot punch through hard lockups and cannot see through
most soft lockups either.
- The SysRq-L code depends on the NMI watchdog - which is off
by default.
- We dont print backtraces from the RCU code's built-in
'RCU state machine is stuck' debug code. This debug
code tends to be one of the first (and only) mechanisms
that show that a lockup has occured.
This patch changes the code so taht we:
- Trigger the NMI backtrace code from SysRq-L instead of using
a workqueue (which cannot punch through hard lockups)
- Trigger print-all-CPU-backtraces from the RCU lockup detection
code
Also decouple the backtrace printing code from the NMI watchdog:
- Dont use variable size cpumasks (it might not be initialized
and they are a bit more fragile anyway)
- Trigger an NMI immediately via an IPI, instead of waiting
for the NMI tick to occur. This is a lot faster and can
produce more relevant backtraces. It will also work if the
NMI watchdog is disabled.
- Dont print the 'dazed and confused' message when we print
a backtrace from the NMI
- Do a show_regs() plus a dump_stack() to get maximum info
out of the dump. Worst-case we get two stacktraces - which
is not a big deal. Sometimes, if register content is
corrupted, the precise stack walker in show_regs() wont
give us a full backtrace - in this case dump_stack() will
do it.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
io context: fix ref counting
block: make the end_io functions be non-GPL exports
block: fix improper kobject release in blk_integrity_unregister
block: always assign default lock to queues
mg_disk: Add missing ready status check on mg_write()
mg_disk: fix issue with data integrity on error in mg_write()
mg_disk: fix reading invalid status when use polling driver
mg_disk: remove prohibited sleep operation
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc:
mmc: orphan subsystem
imxmmc: Remove unnecessary semicolons
cb710: use SG_MITER_TO_SG/SG_MITER_FROM_SG
sdhci: use SG_MITER_TO_SG/SG_MITER_FROM_SG
lib/scatterlist: add a flags to signalize mapping direction
To fix the common case where ->enable() does not set up
mult, make sure mult_orig is saved in mult on disable.
Also add comments to explain why we do this.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Cc: johnstul@us.ibm.com
Cc: lethal@linux-sh.org
Cc: akpm@linux-foundation.org
LKML-Reference: <20090618152432.10136.9932.sendpatchset@rx1.opensource.se>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
the code allready uses flush_kernel_dcache_page(). This patch updates the
driver to the recent sg API changes which require that either SG_MITER_TO_SG
or SG_MITER_FROM_SG is set. SG_MITER_TO_SG calls flush_kernel_dcache_page()
in sg_mitter_stop()
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Acked-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>
so the page will be flushed on unmap on ARCH which need it.
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>
sg_miter_start() is currently unaware of the direction of the copy
process (to or from the scatter list). It is important to know the
direction because the page has to be flushed in case the data written
is seen on a different mapping in user land on cache incoherent
architectures.
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>
Check that the result of kzalloc is not NULL before a dereference.
The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@@
expression *x;
identifier f;
constant char *C;
@@
x = \(kmalloc\|kcalloc\|kzalloc\)(...);
... when != x == NULL
when != x != NULL
when != (x || ...)
(
kfree(x)
|
f(...,C,...,x,...)
|
*f(...,x,...)
|
*x->f
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
The name buf with size 16 is too short for some codec names, e.g.
truncated like "ALC861-VD Analo". Now the size is doubled.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
VM calculation for nr_to_write seems off. Bump it way
up, this gets simple streaming writes zippy again.
To be reviewed again after Jens' writeback changes.
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Cc: Chris Mason <chris.mason@oracle.com>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
commit 6321e3ed2a caused
the full bmv_count's worth of getbmapx structures to get
allocated; telling it to do MAXEXTNUM was a bit insane,
resulting in ENOMEM every time.
Chop it down to something reasonable, the number of slots
in the caller's input buffer. If this is too large the
caller may get ENOMEM but the reason should not be a
mystery, and they can try again with something smaller.
We add 1 to the value because in the normal getbmap
world, bmv_count includes the header and xfs_getbmap does:
nex = bmv->bmv_count - 1;
if (nex <= 0)
return XFS_ERROR(EINVAL);
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Olaf Weber <olaf@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
Btrfs: be more polite in the async caching threads
Btrfs: preserve commit_root for async caching
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx:
dmaengine: at_hdmac: add DMA slave transfers
dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller
dmaengine: dmatest: correct thread_count while using multiple thread per channel
dmaengine: dmatest: add a maximum number of test iterations
drivers/dma: Remove unnecessary semicolons
drivers/dma/fsldma.c: Remove unnecessary semicolons
dmaengine: move HIGHMEM64G restriction to ASYNC_TX_DMA
fsldma: do not clear bandwidth control bits on the 83xx controller
fsldma: enable external start for the 83xx controller
fsldma: use PCI Read Multiple command
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6:
udf: Fix loading of VAT inode when drive wrongly reports number of recorded blocks
* git://git.infradead.org/users/cbou/battery-2.6.31:
Add ds2782 battery gas gauge driver
olpc_battery: Ensure that the TRICKLE bit is checked
olpc_battery: Fix up eeprom read function
* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes:
GFS2: remove dcache entries for remote deleted inodes
GFS2: Fix incorrent statfs consistency check
GFS2: Don't put unlikely reclaim candidates on the reclaim list.
GFS2: Don't try and dealloc own inode
GFS2: Fix panic in glock memory shrinker
GFS2: keep statfs info in sync on grows
GFS2: Shrink the shrinker
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc:
powerpc: Update defconfigs for embedded 6xx/7xxx, 8xx, 8{3,5,6}xxx
powerpc/86xx: Update GE Fanuc sbc310 default configuration
powerpc/86xx: Update defconfig for GE Fanuc's PPC9A
cpm_uart: Don't use alloc_bootmem in cpm_uart_cpm2.c
powerpc/83xx: Fix PCI IO base address on MPC837xE-RDB boards
powerpc/85xx: Don't scan for TBI PHY addresses on MPC8569E-MDS boards
powerpc/85xx: Fix ethernet link detection on MPC8569E-MDS boards
powerpc/mm: Fix SMP issue with MMU context handling code
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
lguest and virtio: cleanup struct definitions to Linux style.
lguest: update commentry
lguest: fix comment style
virtio: refactor find_vqs
virtio: delete vq from list
virtio: fix memory leak on device removal
lguest: fix descriptor corruption in example launcher
lguest: dereferencing freed mem in add_eventfd()
Use kernel_text_address() for checking probe address instead of
__kernel_text_address(), because __kernel_text_address() returns true
for init functions even after relaseing those functions.
That will hit a BUG() in text_poke().
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Not that anybody can blame him. It's a morass. But hey, it's way
better than it _used_ to be, though, so thanks for all the fish.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit d01730d74d didn't completely fix
the problem since we still take dqio_mutex and i_mutex in the wrong
order. Move taking of i_mutex further down (luckily it's needed only
for updating inode flags) below where dqio_mutex is taken.
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
VAT inode is located in the last block recorded block of the medium. When the
drive errorneously reports number of recorded blocks, we failed to load the VAT
inode and thus mount the medium. This patch makes kernel try to read VAT inode
from the last block of the device if it is different from the last recorded
block.
Signed-off-by: Jan Kara <jack@suse.cz>
The semaphore used by the async caching threads can prevent a
transaction commit, which can make the FS appear to stall. This
releases the semaphore more often when a transaction commit is
in progress.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The async block group caching code uses the commit_root pointer
to get a stable version of the extent allocation tree for scanning.
This copy of the tree root isn't going to change and it significantly
reduces the complexity of the scanning code.
During a commit, we have a loop where we update the extent allocation
tree root. We need to loop because updating the root pointer in
the tree of tree roots may allocate blocks which may change the
extent allocation tree.
Right now the commit_root pointer is changed inside this loop. It
is more correct to change the commit_root pointer only after all the
looping is done.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
When a file is deleted from a gfs2 filesystem on one node, a dcache
entry for it may still exist on other nodes in the cluster. If this
happens, gfs2 will be unable to free this file on disk. Because of this,
it's possible to have a gfs2 filesystem with no files on it and no free
space. With this patch, when a node receives a callback notifying it
that the file is being deleted on another node, it schedules a new
workqueue thread to remove the file's dcache entry.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Since both linked and unlinked inodes are counted by rgd->rd_dinodes, It
makes no sense to count them with the used data blocks (first check that
I changed), it makes sense to count them with the linked inodes (second
check), and it makes no sense to care if there are more unlinked inodes
than linked ones. This fixes these errors.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
GFS2 was placing far too many glocks on the reclaim list that were not good
candidates for freeing up from cache. These locks would sit there and
repeatedly get scanned to see if they could be reclaimed, wasting a lot
of time when there was memory pressure. This fix does more checks on the
locks to see if they are actually likely to be removable from cache.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
When searching for unlinked, but still allocated inodes during block
allocation, avoid the block relating to the inode that is doing the
allocation. This fixes a hang caused when an unlinked, but still
open, inode tries to allocate some more blocks and lands up
finding itself during the search for deallocatable inodes.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
It is possible for gfs2_shrink_glock_memory() to check a glock for
demotion
that's in the process of being freed by gfs2_glock_put(). In this case,
gfs2_shrink_glock_memory() will acquire a new reference to this glock,
and
then try to free the glock itself when it drops the refernce. To solve
this, gfs2_shrink_glock_memory() just needs to check if the glock is in
the process of being freed, and if so skip it without ever unlocking the
lru_lock.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Acked-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
GFS2 wasn't syncing its statfs info on grows. This causes a problem
when you grow the filesystem on multiple nodes. GFS2 would calculate
the new space based on the resource groups (which are always current),
and then assume that the filesystem had grown the from the existing
statfs size. If you grew the filesystem on two different nodes in a
short time, the second node wouldn't see the statfs size change from the
first node, and would assume that it was grown by a larger amount than
it was. When all these changes were synced out, the total fileystem
size would be incorrect (the first grow would be counted twice).
This patch syncs makes GFS2 read in the statfs changes from disk before
a grow, and write them out after the grow, while the master statfs inode
is locked.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch removes some of the special cases that the shrinker
was trying to deal with. As a result we leave fewer items on
the list and none at all which cannot be demoted. This makes
the list scanning more efficient and solves some issues seen
with large numbers of inodes.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
I've been doing this for years, and akpm picked me up on it about 12
months ago. lguest partly serves as example code, so let's do it Right.
Also, remove two unused fields in struct vblk_info in the example launcher.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Every so often, after code shuffles, I need to go through and unbitrot
the Lguest Journey (see drivers/lguest/README). Since we now use RCU in
a simple form in one place I took the opportunity to expand that explanation.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does. And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
This refactors find_vqs, making it more readable and robust, and fixing
two regressions from 2.6.30:
- double free_irq causing BUG_ON on device removal
- probe failure when vq can't be assigned to msi-x vector
(reported on old host kernels)
Tested-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This makes delete vq the reverse of find vq.
This is required to make it possible to retry find_vqs
after a failure, otherwise the list gets corrupted.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Make vp_free_vectors do the reverse of vq_request_vectors.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
1d589bb16b "Add serial number support
for virtio_blk, V4a" extended 'struct virtio_blk_config' to 536 bytes.
Lguest and S/390 both use an 8 bit value for the feature length, and
this change broke them (if the code is naive).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: John Cooper <john.cooper@redhat.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
