per_cpu_ptr_to_phys() incorrectly rounds up its result for non-kmalloc
case to the page boundary, which is bogus for any non-page-aligned
address.
This affects the only in-tree user of this function - sysfs handler
for per-cpu 'crash_notes' physical address. The trouble is that the
crash_notes per-cpu variable is not page-aligned:
crash_notes = 0xc08e8ed4
PER-CPU OFFSET VALUES:
CPU 0: 3711f000
CPU 1: 37129000
CPU 2: 37133000
CPU 3: 3713d000
So, the per-cpu addresses are:
crash_notes on CPU 0: f7a07ed4 => phys 36b57ed4
crash_notes on CPU 1: f7a11ed4 => phys 36b4ded4
crash_notes on CPU 2: f7a1bed4 => phys 36b43ed4
crash_notes on CPU 3: f7a25ed4 => phys 36b39ed4
However, /sys/devices/system/cpu/cpu*/crash_notes says:
/sys/devices/system/cpu/cpu0/crash_notes: 36b57000
/sys/devices/system/cpu/cpu1/crash_notes: 36b4d000
/sys/devices/system/cpu/cpu2/crash_notes: 36b43000
/sys/devices/system/cpu/cpu3/crash_notes: 36b39000
As you can see, all values are rounded down to a page
boundary. Consequently, this is where kexec sets up the NOTE segments,
and thus where the secondary kernel is looking for them. However, when
the first kernel crashes, it saves the notes to the unaligned
addresses, where they are not found.
Fix it by adding offset_in_page() to the translated page address.
-tj: Combined Eugene's and Petr's commit messages.
Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Petr Tesarik <ptesarik@suse.cz>
Cc: stable@kernel.org
Add comments about current per_cpu_ptr_to_phys implementation to
explain why the logic is more complicated than necessary.
-tj: relocated comment into kerneldoc comment
Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Percpu allocator recorded the cpus which map to the first and last
units in pcpu_first/last_unit_cpu respectively and used them to
determine the address range of a chunk - e.g. it assumed that the
first unit has the lowest address in a chunk while the last unit has
the highest address.
This simply isn't true. Groups in a chunk can have arbitrary positive
or negative offsets from the previous one and there is no guarantee
that the first unit occupies the lowest offset while the last one the
highest.
Fix it by actually comparing unit offsets to determine cpus occupying
the lowest and highest offsets. Also, rename pcu_first/last_unit_cpu
to pcpu_low/high_unit_cpu to avoid confusion.
The chunk address range is used to flush cache on vmalloc area
map/unmap and decide whether a given address is in the first chunk by
per_cpu_ptr_to_phys() and the bug was discovered by invalid
per_cpu_ptr_to_phys() translation for crash_note.
Kudos to Dave Young for tracking down the problem.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: WANG Cong <xiyou.wangcong@gmail.com>
Reported-by: Dave Young <dyoung@redhat.com>
Tested-by: Dave Young <dyoung@redhat.com>
LKML-Reference: <4EC21F67.10905@redhat.com>
Cc: stable @kernel.org
Currently pcpu_mem_alloc() is implemented always return zeroed memory.
So rename it to make user like pcpu_get_pages_and_bitmap() know don't
reinit it.
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
* 'for-2.6.40' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: Unify input section names
percpu: Avoid extra NOP in percpu_cmpxchg16b_double
percpu: Cast away printk format warning
percpu: Always align percpu output section to PAGE_SIZE
Fix up fairly trivial conflict in arch/x86/include/asm/percpu.h as per Tejun
On 32-bit systems which don't happen to implicitly define or cast
VMALLOC_START and/or VMALLOC_END to long in their arch headers, the
printk in the percpu code will cause a warning to be emitted:
mm/percpu.c: In function 'pcpu_embed_first_chunk':
mm/percpu.c:1648: warning: format '%lx' expects type 'long unsigned int',
but argument 3 has type 'unsigned int'
So add an explicit cast to unsigned long here.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
per_cpu_ptr_to_phys() uses VMALLOC_START and VMALLOC_END to determine if an
address is in the vmalloc() region or not. This is incorrect on NOMMU as
there is no real vmalloc() capability (vmalloc() is emulated by kmalloc()).
The correct way to do this is to use is_vmalloc_addr(). This encapsulates the
vmalloc() region test in MMU mode and just returns 0 in NOMMU mode.
On FRV in NOMMU mode, the percpu compilation fails without this patch:
mm/percpu.c: In function 'per_cpu_ptr_to_phys':
mm/percpu.c:1011: error: 'VMALLOC_START' undeclared (first use in this function)
mm/percpu.c:1011: error: (Each undeclared identifier is reported only once
mm/percpu.c:1011: error: for each function it appears in.)
mm/percpu.c:1012: error: 'VMALLOC_END' undeclared (first use in this function)
mm/percpu.c:1018: warning: control reaches end of non-void function
Signed-off-by: David Howells <dhowells@redhat.com>
Percpu allocator honors alignment request upto PAGE_SIZE and both the
percpu addresses in the percpu address space and the translated kernel
addresses should be aligned accordingly. The calculation of the
former depends on the alignment of percpu output section in the kernel
image.
The linker script macros PERCPU_VADDR() and PERCPU() are used to
define this output section and the latter takes @align parameter.
Several architectures are using @align smaller than PAGE_SIZE breaking
percpu memory alignment.
This patch removes @align parameter from PERCPU(), renames it to
PERCPU_SECTION() and makes it always align to PAGE_SIZE. While at it,
add PCPU_SETUP_BUG_ON() checks such that alignment problems are
reliably detected and remove percpu alignment comment recently added
in workqueue.c as the condition would trigger BUG way before reaching
there.
For um, this patch raises the alignment of percpu area. As the area
is in .init, there shouldn't be any noticeable difference.
This problem was discovered by David Howells while debugging boot
failure on mn10300.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Cc: David Howells <dhowells@redhat.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
gameport: use this_cpu_read instead of lookup
x86: udelay: Use this_cpu_read to avoid address calculation
x86: Use this_cpu_inc_return for nmi counter
x86: Replace uses of current_cpu_data with this_cpu ops
x86: Use this_cpu_ops to optimize code
vmstat: User per cpu atomics to avoid interrupt disable / enable
irq_work: Use per cpu atomics instead of regular atomics
cpuops: Use cmpxchg for xchg to avoid lock semantics
x86: this_cpu_cmpxchg and this_cpu_xchg operations
percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
percpu,x86: relocate this_cpu_add_return() and friends
connector: Use this_cpu operations
xen: Use this_cpu_inc_return
taskstats: Use this_cpu_ops
random: Use this_cpu_inc_return
fs: Use this_cpu_inc_return in buffer.c
highmem: Use this_cpu_xx_return() operations
vmstat: Use this_cpu_inc_return for vm statistics
x86: Support for this_cpu_add, sub, dec, inc_return
percpu: Generic support for this_cpu_add, sub, dec, inc_return
...
Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
Now that percpu allocator is mostly stable, there is no reason to
print alloc information with KERN_INFO and clutter the boot messages.
Switch it to KERN_DEBUG.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Travis <travis@sgi.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: update comments to reflect that percpu allocations are always zero-filled
percpu: Optimize __get_cpu_var()
x86, percpu: Optimize this_cpu_ptr
percpu: clear memory allocated with the km allocator
percpu: fix build breakage on s390 and cleanup build configuration tests
percpu: use percpu allocator on UP too
percpu: reduce PCPU_MIN_UNIT_SIZE to 32k
vmalloc: pcpu_get/free_vm_areas() aren't needed on UP
Fixed up trivial conflicts in include/linux/percpu.h
pcpu_first/last_unit_cpu are used to track which cpu has the first and
last units assigned. This in turn is used to determine the span of a
chunk for man/unmap cache flushes and whether an address belongs to
the first chunk or not in per_cpu_ptr_to_phys().
When the number of possible CPUs isn't power of two, a chunk may
contain unassigned units towards the end of a chunk. The logic to
determine pcpu_last_unit_cpu was incorrect when there was an unused
unit at the end of a chunk. It failed to ignore the unused unit and
assigned the unused marker NR_CPUS to pcpu_last_unit_cpu.
This was discovered through kdump failure which was caused by
malfunctioning per_cpu_ptr_to_phys() on a kvm setup with 50 possible
CPUs by CAI Qian.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: CAI Qian <caiqian@redhat.com>
Cc: stable@kernel.org
Commit bbddff05 (percpu: use percpu allocator on UP too) incorrectly
excluded pcpu_build_alloc_info() on SMP configurations which use
generic setup_per_cpu_area() like s390. The config ifdefs are
becoming confusing. Fix and clean it up by,
* Move pcpu_build_alloc_info() right on top of its two users -
pcpu_{embed|page}_first_chunk() which are already in CONFIG_SMP
block.
* Define BUILD_{EMBED|PAGE}_FIRST_CHUNK which indicate whether each
first chunk function needs to be included and use them to control
inclusion of the three functions to reduce confusion.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sachin Sant <sachinp@in.ibm.com>
On UP, percpu allocations were redirected to kmalloc. This has the
following problems.
* For certain amount of allocations (determined by
PERCPU_DYNAMIC_EARLY_SLOTS and PERCPU_DYNAMIC_EARLY_SIZE), percpu
allocator can be used before the usual kernel memory allocator is
brought online. On SMP, this is used to initialize the kernel
memory allocator.
* percpu allocator honors alignment upto PAGE_SIZE but kmalloc()
doesn't. For example, workqueue makes use of larger alignments for
cpu_workqueues.
Currently, users of percpu allocators need to handle UP differently,
which is somewhat fragile and ugly. Other than small amount of
memory, there isn't much to lose by enabling percpu allocator on UP.
It can simply use kernel memory based chunk allocation which was added
for SMP archs w/o MMUs.
This patch removes mm/percpu_up.c, builds mm/percpu.c on UP too and
makes UP build use percpu-km. As percpu addresses and kernel
addresses are always identity mapped and static percpu variables don't
need any special treatment, nothing is arch dependent and mm/percpu.c
implements generic setup_per_cpu_areas() for UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
When pcpu_build_alloc_info() searches best_upa value, it ignores current value
if the number of waste units exceeds 1/3 of the number of total cpus. But the
comment on the code says that it will ignore if wastage is over 25%.
Modify the comment.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The original code did not free the old map. This patch fixes it.
tj: use @old as memcpy source instead of @chunk->map, and indentation
and description update
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
This patch updates percpu allocator such that it can serve limited
amount of allocation before slab comes online. This is primarily to
allow slab to depend on working percpu allocator.
Two parameters, PERCPU_DYNAMIC_EARLY_SIZE and SLOTS, determine how
much memory space and allocation map slots are reserved. If this
reserved area is exhausted, WARN_ON_ONCE() will trigger and allocation
will fail till slab comes online.
The following changes are made to implement early alloc.
* pcpu_mem_alloc() now checks slab_is_available()
* Chunks are allocated using pcpu_mem_alloc()
* Init paths make sure ai->dyn_size is at least as large as
PERCPU_DYNAMIC_EARLY_SIZE.
* Initial alloc maps are allocated in __initdata and copied to
kmalloc'd areas once slab is online.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
In pcpu_build_alloc_info() and pcpu_embed_first_chunk(), @dyn_size was
ssize_t, -1 meant auto-size, 0 forced 0 and positive meant minimum
size. There's no use case for forcing 0 and the upcoming early alloc
support always requires non-zero dynamic size. Make @dyn_size always
mean minimum dyn_size.
While at it, make pcpu_build_alloc_info() static which doesn't have
any external caller as suggested by David Rientjes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
per_cpu_ptr_to_phys() determines whether the passed in @addr belongs
to the first_chunk or not by just matching the address against the
address range of the base unit (unit0, used by cpu0). When an adress
from another cpu was passed in, it will always determine that the
address doesn't belong to the first chunk even when it does. This
makes the function return a bogus physical address which may lead to
crash.
This problem was discovered by Cliff Wickman while investigating a
crash during kdump on a SGI UV system.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Cliff Wickman <cpw@sgi.com>
Tested-by: Cliff Wickman <cpw@sgi.com>
Cc: stable@kernel.org
Fix the following two trivial bugs in pcpu_build_alloc_info()
* we should memset group_cnt to 0 by size of group_cnt, not size of
group_map (both are of the same size, so the bug isn't dangerous)
* we can delete useless variable group_cnt_max.
Signed-off-by: Pavel V. Panteleev <pp_84@mail.ru>
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement an alternate percpu chunk management based on kernel memeory
for nommu SMP architectures. Instead of mapping into vmalloc area,
chunks are allocated as a contiguous kernel memory using
alloc_pages(). As such, percpu allocator on nommu will have the
following restrictions.
* It can't fill chunks on-demand page-by-page. It has to allocate
each chunk fully upfront.
* It can't support sparse chunk for NUMA configurations. SMP w/o mmu
is crazy enough. Let's hope no one does NUMA w/o mmu. :-P
* If chunk size isn't power-of-two multiple of PAGE_SIZE, the
unaligned amount will be wasted on each chunk. So, archs which use
this better align chunk size.
For instructions on how to use this, read the comment on top of
mm/percpu-km.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Separate out and move chunk management (creation/desctruction and
[de]population) code into percpu-vm.c which is included by percpu.c
and compiled together. The interface for chunk management is defined
as follows.
* pcpu_populate_chunk - populate the specified range of a chunk
* pcpu_depopulate_chunk - depopulate the specified range of a chunk
* pcpu_create_chunk - create a new chunk
* pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
* pcpu_addr_to_page - translate address to physical address
* pcpu_verify_alloc_info - check alloc_info is acceptable during init
Other than wrapping vmalloc_to_page() inside pcpu_addr_to_page() and
dummy pcpu_verify_alloc_info() implementation, this patch only moves
code around. This separation is to allow alternate chunk management
implementation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Make the following misc preparations for percpu nommu support.
* Remove refernces to vmalloc in common comments as nommu percpu won't
use it.
* Rename chunk->vms to chunk->data and make it void *. Its use is
determined by chunk management implementation.
* Relocate utility functions and add __maybe_unused to functions which
might not be used by different chunk management implementations.
This patch doesn't cause any functional change. This is to allow
alternate chunk management implementation for percpu nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Reorganize alloc/free_pcpu_chunk() such that chunk struct alloc/free
live in pcpu_alloc/free_chunk() and the rest in
pcpu_create/destroy_chunk(). While at it, add missing error handling
for chunk->map allocation failure.
This is to allow alternate chunk management implementation for percpu
nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
Factor out pcpu_addr_in_first/reserved_chunk() from
pcpu_chunk_addr_search() and use it to update per_cpu_ptr_to_phys()
such that it handles first chunk differently from the rest.
This patch doesn't cause any functional change and is to prepare for
percpu nommu support.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Graff Yang <graff.yang@gmail.com>
Cc: Sonic Zhang <sonic.adi@gmail.com>
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>
Add __percpu sparse annotations to core subsystems.
These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors. This patch doesn't affect normal builds.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-mm@kvack.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biederman <ebiederm@xmission.com>
__pcpu_ptr_to_addr() can be overridden by the architecture and might not
behave well if passed a NULL pointer. So avoid calling it until we have
verified that its arg is not NULL.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
With ia64 converted, there's no arch left which still uses legacy
percpu allocator. Kill it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Delightedly-acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
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>
