linux-stable.git/mm/cma.c, branch linux-4.2.y

mm/memblock: add extra "flags" to memblock to allow selection of memory based on attribute

2015-06-25T00:49:44+00:00

Some high end Intel Xeon systems report uncorrectable memory errors as a
recoverable machine check.  Linux has included code for some time to
process these and just signal the affected processes (or even recover
completely if the error was in a read only page that can be replaced by
reading from disk).

But we have no recovery path for errors encountered during kernel code
execution.  Except for some very specific cases were are unlikely to ever
be able to recover.

Enter memory mirroring. Actually 3rd generation of memory mirroing.

Gen1: All memory is mirrored
	Pro: No s/w enabling - h/w just gets good data from other side of the
	     mirror
	Con: Halves effective memory capacity available to OS/applications

Gen2: Partial memory mirror - just mirror memory begind some memory controllers
	Pro: Keep more of the capacity
	Con: Nightmare to enable. Have to choose between allocating from
	     mirrored memory for safety vs. NUMA local memory for performance

Gen3: Address range partial memory mirror - some mirror on each memory
      controller
	Pro: Can tune the amount of mirror and keep NUMA performance
	Con: I have to write memory management code to implement

The current plan is just to use mirrored memory for kernel allocations.
This has been broken into two phases:

1) This patch series - find the mirrored memory, use it for boot time
   allocations

2) Wade into mm/page_alloc.c and define a ZONE_MIRROR to pick up the
   unused mirrored memory from mm/memblock.c and only give it out to
   select kernel allocations (this is still being scoped because
   page_alloc.c is scary).

This patch (of 3):

Add extra "flags" to memblock to allow selection of memory based on
attribute.  No functional changes

Signed-off-by: Tony Luck 
Cc: Xishi Qiu 
Cc: Hanjun Guo 
Cc: Xiexiuqi 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Yinghai Lu 
Cc: Naoya Horiguchi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/cma.c: fix typos in comments

2015-06-25T00:49:44+00:00

Signed-off-by: Shailendra Verma 
Acked-by: Michal Nazarewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: add trace events for CMA allocations and freeings

2015-04-15T23:35:19+00:00

Add trace events for cma_alloc() and cma_release().

The cma_alloc tracepoint is used both for successful and failed allocations,
in case of allocation failure pfn=-1UL is stored and printed.

Signed-off-by: Stefan Strogin 
Cc: Ingo Molnar 
Cc: Steven Rostedt 
Cc: Joonsoo Kim 
Cc: Michal Nazarewicz 
Cc: Marek Szyprowski 
Cc: Laurent Pinchart 
Cc: Thierry Reding 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: constify and use correct signness in mm/cma.c

2015-04-14T23:49:04+00:00

Constify function parameters and use correct signness where needed.

Signed-off-by: Sasha Levin 
Cc: Michal Nazarewicz 
Cc: Marek Szyprowski 
Cc: Joonsoo Kim 
Cc: Laurent Pinchart 
Acked-by: Gregory Fong 
Cc: Pintu Kumar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: allocation trigger

2015-04-14T23:49:00+00:00

Provides a userspace interface to trigger a CMA allocation.

Usage:

        echo [pages] > alloc

This would provide testing/fuzzing access to the CMA allocation paths.

Signed-off-by: Sasha Levin 
Acked-by: Joonsoo Kim 
Cc: Marek Szyprowski 
Cc: Laura Abbott 
Cc: Konrad Rzeszutek Wilk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: debugfs interface

2015-04-14T23:49:00+00:00

I've noticed that there is no interfaces exposed by CMA which would let me
fuzz what's going on in there.

This small patchset exposes some information out to userspace, plus adds
the ability to trigger allocation and freeing from userspace.

This patch (of 3):

Implement a simple debugfs interface to expose information about CMA areas
in the system.

Useful for testing/sanity checks for CMA since it was impossible to
previously retrieve this information in userspace.

Signed-off-by: Sasha Levin 
Acked-by: Joonsoo Kim 
Cc: Marek Szyprowski 
Cc: Laura Abbott 
Cc: Konrad Rzeszutek Wilk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: fix CMA aligned offset calculation

2015-03-13T01:46:07+00:00

The CMA aligned offset calculation is incorrect for non-zero order_per_bit
values.

For example, if cma->order_per_bit=1, cma->base_pfn= 0x2f800000 and
align_order=12, the function returns a value of 0x17c00 instead of 0x400.

This patch fixes the CMA aligned offset calculation.

The previous calculation was wrong and would return too-large values for
the offset, so that when cma_alloc looks for free pages in the bitmap with
the requested alignment > order_per_bit, it starts too far into the bitmap
and so CMA allocations will fail despite there actually being plenty of
free pages remaining.  It will also probably have the wrong alignment.
With this change, we will get the correct offset into the bitmap.

One affected user is powerpc KVM, which has kvm_cma->order_per_bit set to
KVM_CMA_CHUNK_ORDER - PAGE_SHIFT, or 18 - 12 = 6.

[gregory.0xf0@gmail.com: changelog additions]
Signed-off-by: Danesh Petigara 
Reviewed-by: Gregory Fong 
Acked-by: Michal Nazarewicz 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: fix totalcma_pages to include DT defined CMA regions

2015-02-12T01:06:03+00:00

The totalcma_pages variable is not updated to account for CMA regions
defined via device tree reserved-memory sub-nodes.  Fix this omission by
moving the calculation of totalcma_pages into cma_init_reserved_mem()
instead of cma_declare_contiguous() such that it will include reserved
memory used by all CMA regions.

Signed-off-by: George G. Davis 
Cc: Marek Szyprowski 
Acked-by: Michal Nazarewicz 
Cc: Joonsoo Kim 
Cc: "Aneesh Kumar K.V" 
Cc: Laurent Pinchart 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: cma: split cma-reserved in dmesg log

2014-12-19T03:08:10+00:00

When the system boots up, in the dmesg logs we can see the memory
statistics along with total reserved as below.  Memory: 458840k/458840k
available, 65448k reserved, 0K highmem

When CMA is enabled, still the total reserved memory remains the same.
However, the CMA memory is not considered as reserved.  But, when we see
/proc/meminfo, the CMA memory is part of free memory.  This creates
confusion.  This patch corrects the problem by properly subtracting the
CMA reserved memory from the total reserved memory in dmesg logs.

Below is the dmesg snapshot from an arm based device with 512MB RAM and
12MB single CMA region.

Before this change:
  Memory: 458840k/458840k available, 65448k reserved, 0K highmem

After this change:
  Memory: 458840k/458840k available, 53160k reserved, 12288k cma-reserved, 0K highmem

Signed-off-by: Pintu Kumar 
Signed-off-by: Vishnu Pratap Singh 
Acked-by: Michal Nazarewicz 
Cc: Rafael Aquini 
Cc: Jerome Marchand 
Cc: Marek Szyprowski 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/cma: make kmemleak ignore CMA regions

2014-12-13T20:42:53+00:00

kmemleak will add allocations as objects to a pool.  The memory allocated
for each object in this pool is periodically searched for pointers to
other allocated objects.  This only works for memory that is mapped into
the kernel's virtual address space, which happens not to be the case for
most CMA regions.

Furthermore, CMA regions are typically used to store data transferred to
or from a device and therefore don't contain pointers to other objects.

Without this, the kernel crashes on the first execution of the
scan_gray_list() because it tries to access highmem.  Perhaps a more
appropriate fix would be to reject any object that can't map to a kernel
virtual address?

[akpm@linux-foundation.org: add comment]
[akpm@linux-foundation.org: fix comment, per Catalin]
[sfr@canb.auug.org.au: include linux/io.h for phys_to_virt()]
Signed-off-by: Thierry Reding 
Cc: Michal Nazarewicz 
Cc: Marek Szyprowski 
Cc: Joonsoo Kim 
Cc: "Aneesh Kumar K.V" 
Cc: Catalin Marinas 
Signed-off-by: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds