Add a function that operates on the second doubleword in the page struct
and manipulates the object counters, the freelist and the frozen attribute.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This is necessary because the frozen bit has to be handled in the same cmpxchg_double
with the freelist and the counters.
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Do not use a page flag for the frozen bit. It needs to be part
of the state that is handled with cmpxchg_double(). So use a bit
in the counter struct in the page struct for that purpose.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Do the irq handling in allocate_slab() instead of __slab_alloc().
__slab_alloc() is already cluttered and allocate_slab() is already
fiddling around with gfp flags.
v6->v7:
Only increment ORDER_FALLBACK if we get a page during fallback
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
On an architecture without CMPXCHG_LOCAL but with DEBUG_VM enabled,
the VM_BUG_ON() in __pcpu_double_call_return_bool() will cause an early
panic during boot unless we always align cpu_slab properly.
In principle we could remove the alignment-testing VM_BUG_ON() for
architectures that don't have CMPXCHG_LOCAL, but leaving it in means
that new code will tend not to break x86 even if it is introduced
on another platform, and it's low cost to require alignment.
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Commit a71ae47a2c ("slub: Fix double bit unlock in debug mode")
removed the only goto to this label, resulting in
mm/slub.c: In function '__slab_alloc':
mm/slub.c:1834: warning: label 'unlock_out' defined but not used
fixed trivially by the removal of the label itself too.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 442b06bcea ("slub: Remove node check in slab_free") added a
call to deactivate_slab() in the debug case in __slab_alloc(), which
unlocks the current slab used for allocation. Going to the label
'unlock_out' then does it again.
Also, in the debug case we do not need all the other processing that the
'unlock_out' path does. We always fall back to the slow path in the
debug case. So the tid update is useless.
Similarly, ALLOC_SLOWPATH would just be incremented for all allocations.
Also a pretty useless thing.
So simply restore irq flags and return the object.
Signed-off-by: Christoph Lameter <cl@linux.com>
Reported-and-bisected-by: James Morris <jmorris@namei.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Jens Axboe <jaxboe@fusionio.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can set the page pointing in the percpu structure to
NULL to have the same effect as setting c->node to NUMA_NO_NODE.
Gets rid of one check in slab_free() that was only used for
forcing the slab_free to the slowpath for debugging.
We still need to set c->node to NUMA_NO_NODE to force the
slab_alloc() fastpath to the slowpath in case of debugging.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Jumping to a label inside a conditional is considered poor style,
especially considering the current organization of __slab_alloc().
This removes the 'load_from_page' label and just duplicates the three
lines of code that it uses:
c->node = page_to_nid(page);
c->page = page;
goto load_freelist;
since it's probably not worth making this a separate helper function.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Fastpath can do a speculative access to a page that CONFIG_DEBUG_PAGE_ALLOC may have
marked as invalid to retrieve the pointer to the next free object.
Use probe_kernel_read in that case in order not to cause a page fault.
Cc: <stable@kernel.org> # 38.x
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Move the #ifdef so that get_map is only defined if CONFIG_SLUB_DEBUG is defined.
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Remove the #ifdefs. This means that the irqsafe_cpu_cmpxchg_double() is used
everywhere.
There may be performance implications since:
A. We now have to manage a transaction ID for all arches
B. The interrupt holdoff for arches not supporting CONFIG_CMPXCHG_LOCAL is reduced
to a very short irqoff section.
There are no multiple irqoff/irqon sequences as a result of this change. Even in the fallback
case we only have to do one disable and enable like before.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The SLUB allocator use of the cmpxchg_double logic was wrong: it
actually needs the irq-safe one.
That happens automatically when we use the native unlocked 'cmpxchg8b'
instruction, but when compiling the kernel for older x86 CPUs that do
not support that instruction, we fall back to the generic emulation
code.
And if you don't specify that you want the irq-safe version, the generic
code ends up just open-coding the cmpxchg8b equivalent without any
protection against interrupts or preemption. Which definitely doesn't
work for SLUB.
This was reported by Werner Landgraf <w.landgraf@ru.ru>, who saw
instability with his distro-kernel that was compiled to support pretty
much everything under the sun. Most big Linux distributions tend to
compile for PPro and later, and would never have noticed this problem.
This also fixes the prototypes for the irqsafe cmpxchg_double functions
to use 'bool' like they should.
[ Btw, that whole "generic code defaults to no protection" design just
sounds stupid - if the code needs no protection, there is no reason to
use "cmpxchg_double" to begin with. So we should probably just remove
the unprotected version entirely as pointless. - Linus ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reported-and-tested-by: werner <w.landgraf@ru.ru>
Acked-and-tested-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1105041539050.3005@ionos
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Its easier to read if its with the check for debugging flags.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
If the node does not change then there is no need to recalculate
the node from the page struct. So move the node determination
into the places where we acquire a new slab page.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
__slab_alloc is full of "c->page" repeats. Lets just use one local variable
named "page" for this. Also avoids the need to a have another variable
called "new".
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
The bit map of free objects in a slab page is determined in various functions
if debugging is enabled.
Provide a common function for that purpose.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
There's no config named SLAB_DEBUG, and it should be a typo
of SLUB_DEBUG.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
It turns out that the cmpxchg16b emulation has to access vmalloced
percpu memory with interrupts disabled. If the memory has never
been touched before then the fault necessary to establish the
mapping will not to occur and the kernel will fail on boot.
Fix that by reusing the CONFIG_PREEMPT code that writes the
cpu number into a field on every cpu. Writing to the per cpu
area before causes the mapping to be established before we get
to a cmpxchg16b emulation.
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
On Thu, 24 Mar 2011, Ingo Molnar wrote:
> RIP: 0010:[<ffffffff810570a9>] [<ffffffff810570a9>] get_next_timer_interrupt+0x119/0x260
That's a typical timer crash, but you were unable to debug it with
debugobjects because commit d3f661d6 broke those.
Cc: Christoph Lameter <cl@linux.com>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
OOM path is missing the irq restore in the CONFIG_CMPXCHG_LOCAL case.
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Christoph Lameter
Chris Metcalf
Linus Torvalds
Pekka Enberg
David Rientjes
Thomas Gleixner
Li Zefan
Lucas De Marchi