lockdep has custom code to check whether a pointer belongs to static
percpu area which is somewhat broken. Implement proper
is_kernel/module_percpu_address() and replace the custom code.
On UP, percpu variables are regular static variables and can't be
distinguished from them. Always return %false on UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Using break statement at the end of a for loop is confusing,
refactor it by replacing the for loop.
Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
o kdump functionality reserves a per cpu area at boot time and exports the
physical address of that area to user space through sys interface. This
area stores some dump related information like cpu register states etc
at the time of crash.
o We were assuming that per cpu area always come from linearly mapped meory
region and using __pa() to determine physical address.
With percpu_alloc=page, per cpu area can come from vmalloc region also and
__pa() breaks.
o This patch implments a new function to convert per cpu address to
physical address.
Before the patch, crash_notes addresses looked as follows.
cpu0 60fffff49800
cpu1 60fffff60800
cpu2 60fffff77800
These are bogus phsyical addresses.
After the patch, address are following.
cpu0 13eb44000
cpu1 13eb43000
cpu2 13eb42000
cpu3 13eb41000
These look fine. I got 4G of memory and /proc/iomem tell me following.
100000000-13fffffff : System RAM
tj: * added missing asm/io.h include reported by Stephen Rothwell
* repositioned per_cpu_ptr_phys() in percpu.c and added comment.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
pcpu_extend_area_map() had the following two bugs.
* It should return 1 if pcpu_lock was dropped and reacquired but it
returned 0. This could lead to oops if free_percpu() races with
area map extension.
* pcpu_mem_free() was called under pcpu_lock. pcpu_mem_free() might
end up calling vfree() which isn't IRQ safe. This could lead to
deadlock through lock order inversion via IRQ.
In addition, Linus pointed out that the temporary lock dropping and
subtle three-way return value of pcpu_extend_area_map() was very ugly
and suggested to split the function into two - pcpu_need_to_extend()
and pcpu_extend_area_map().
This patch restructures pcpu_extend_area_map() as suggested and fixes
the two bugs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Make the following changes to remove some sparse warnings.
* Make DEFINE_PER_CPU_SECTION() declare __pcpu_unique_* before
defining it.
* Annotate pcpu_extend_area_map() that it is entered with pcpu_lock
held, releases it and then reacquires it.
* Make percpu related macros use unique nested variable names.
* While at it, add pcpu prefix to __size_call[_return]() macros as
to-be-implemented sparse annotations will add percpu specific stuff
to these macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
pcpu_alloc() and pcpu_extend_area_map() perform a series of
spin_lock_irq()/spin_unlock_irq() calls, which make them unsafe
with respect to being called from contexts which have IRQs off.
This patch converts the code to perform save/restore of flags instead,
making pcpu_alloc() (or __alloc_percpu() respectively) to be called
from early kernel startup stage, where IRQs are off.
This is needed for proper initialization of per-cpu rq_weight data from
sched_init().
tj: added comment explaining why irqsave/restore is used in alloc path.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fix the following two compile warnings which show up on i386.
mm/percpu.c:1873: warning: comparison of distinct pointer types lacks a cast
mm/percpu.c:1879: warning: format '%lx' expects type 'long unsigned int', but argument 2 has type 'size_t'
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Warn and dump stack when percpu allocation fails. percpu allocator is
still young and unchecked NULL percpu pointer usage can result in
random memory corruption when combined with the pointer shifting in
access macros. Allocation failures should be rare and the warning
message will be disabled after certain times.
Signed-off-by: Tejun Heo <tj@kernel.org>
The parameters to pcpu_setup_first_chunk() come from different sources
depending on architecture and can be quite complex. The function runs
various sanity checks on the parameters and triggers BUG() if
something isn't right. However, this is very early during the boot
and not reporting exactly what the problem is makes debugging even
harder.
Add PCPU_SETUP_BUG() macro which prints out enough information about
the parameters. As the macro still puts separate BUG() for each
check, it won't lose any information even on the situations where only
the program counter can be retrieved.
While at it, also bump pcpu_dump_alloc_info() message to KERN_INFO so
that it's visible on the console if boot fails to complete.
Signed-off-by: Tejun Heo <tj@kernel.org>
Embedding first chunk allocator maintains the distances between units
in the vmalloc area and thus needs vmalloc space to be larger than the
maximum distances between units; otherwise, it wouldn't be able to
create any dynamic chunks. This patch makes the embedding first chunk
allocator check vmalloc space size and if the maximum distance between
units is larger than 75% of it, print warning and, if page mapping
allocator is available, fail initialization so that the system falls
back onto it.
This should work around percpu allocation failure problems on certain
sparc64 configurations where distances between NUMA nodes are larger
than the vmalloc area and makes percpu allocator more robust for
future configurations.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_build_alloc_info() may be called multiple times when percpu is
falling back to different first chunk allocator. Make it clear static
buffers so that they don't contain values from previous runs.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible
unit number while unit number can equal and go over NR_CPUS with
sparse unit map. This triggers BUG_ON() spuriously on machines which
have non-power-of-two number of cpus. Use UINT_MAX instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Tony Vroon <tony@linx.net>
percpu incorrectly assumed that cpu0 was always there which led to the
following warning and eventual oops on sparc machines w/o cpu0.
WARNING: at mm/percpu.c:651 pcpu_map+0xdc/0x100()
Modules linked in:
Call Trace:
[000000000045eb70] warn_slowpath_common+0x50/0xa0
[000000000045ebdc] warn_slowpath_null+0x1c/0x40
[00000000004d493c] pcpu_map+0xdc/0x100
[00000000004d59a4] pcpu_alloc+0x3e4/0x4e0
[00000000004d5af8] __alloc_percpu+0x18/0x40
[00000000005b112c] __percpu_counter_init+0x4c/0xc0
...
Unable to handle kernel NULL pointer dereference
...
I7: <sysfs_new_dirent+0x30/0x120>
Disabling lock debugging due to kernel taint
Caller[000000000053c1b0]: sysfs_new_dirent+0x30/0x120
Caller[000000000053c7a4]: create_dir+0x24/0xc0
Caller[000000000053c870]: sysfs_create_dir+0x30/0x80
Caller[00000000005990e8]: kobject_add_internal+0xc8/0x200
...
Kernel panic - not syncing: Attempted to kill the idle task!
This patch fixes the problem by backporting parts from devel branch to
make percpu core not depend on the existence of cpu0.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Cc: David Miller <davem@davemloft.net>
With x86 converted to embedding allocator, lpage doesn't have any user
left. Kill it along with cpa handling code.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jan Beulich <JBeulich@novell.com>
Now that percpu core can handle very sparse units, given that vmalloc
space is large enough, embedding first chunk allocator can use any
memory to build the first chunk. This patch teaches
pcpu_embed_first_chunk() about distances between cpus and to use
alloc/free callbacks to allocate node specific areas for each group
and use them for the first chunk.
This brings the benefits of embedding allocator to NUMA configurations
- no extra TLB pressure with the flexibility of unified dynamic
allocator and no need to restructure arch code to build memory layout
suitable for percpu. With units put into atom_size aligned groups
according to cpu distances, using large page for dynamic chunks is
also easily possible with falling back to reuglar pages if large
allocation fails.
Embedding allocator users are converted to specify NULL
cpu_distance_fn, so this patch doesn't cause any visible behavior
difference. Following patches will convert them.
Signed-off-by: Tejun Heo <tj@kernel.org>
ai->groups[] contains which units need to be put consecutively and at
what offset from the chunk base address. Compile this information
into pcpu_group_offsets[] and pcpu_group_sizes[] in
pcpu_setup_first_chunk() and use them to allocate sparse vm areas
using pcpu_get_vm_areas().
This will be used to allow directly using sparse NUMA memories as
percpu areas.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <npiggin@suse.de>
The only thing percpu allocator wants to know about a vmalloc area is
the base address. Instead of requiring chunk->vm, add
chunk->base_addr which contains the necessary value. This simplifies
the code a bit and makes the dummy first_vm unnecessary. This change
will ease allowing a chunk to be mapped by multiple vms.
Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
Andrew Morton
WANG Cong
Vivek Goyal
Jiri Kosina