linux-toradex.git/include/linux/vmalloc.h, branch v4.6-rc6

mm, vmalloc: remove VM_VPAGES

2016-01-15T00:00:49+00:00

VM_VPAGES is unnecessary, it's easier to check is_vmalloc_addr() when
reading /proc/vmallocinfo.

[akpm@linux-foundation.org: remove VM_VPAGES reference via kvfree()]
Signed-off-by: David Rientjes 
Cc: Tetsuo Handa 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: get rid of 'vmalloc_info' from /proc/meminfo

2015-11-02T01:09:15+00:00

It turns out that at least some versions of glibc end up reading
/proc/meminfo at every single startup, because glibc wants to know the
amount of memory the machine has.  And while that's arguably insane,
it's just how things are.

And it turns out that it's not all that expensive most of the time, but
the vmalloc information statistics (amount of virtual memory used in the
vmalloc space, and the biggest remaining chunk) can be rather expensive
to compute.

The 'get_vmalloc_info()' function actually showed up on my profiles as
4% of the CPU usage of "make test" in the git source repository, because
the git tests are lots of very short-lived shell-scripts etc.

It turns out that apparently this same silly vmalloc info gathering
shows up on the facebook servers too, according to Dave Jones.  So it's
not just "make test" for git.

We had two patches to just cache the information (one by me, one by
Ingo) to mitigate this issue, but the whole vmalloc information of of
rather dubious value to begin with, and people who *actually* want to
know what the situation is wrt the vmalloc area should just look at the
much more complete /proc/vmallocinfo instead.

In fact, according to my testing - and perhaps more importantly,
according to that big search engine in the sky: Google - there is
nothing out there that actually cares about those two expensive fields:
VmallocUsed and VmallocChunk.

So let's try to just remove them entirely.  Actually, this just removes
the computation and reports the numbers as zero for now, just to try to
be minimally intrusive.

If this breaks anything, we'll obviously have to re-introduce the code
to compute this all and add the caching patches on top.  But if given
the option, I'd really prefer to just remove this bad idea entirely
rather than add even more code to work around our historical mistake
that likely nobody really cares about.

Signed-off-by: Linus Torvalds

kasan, module, vmalloc: rework shadow allocation for modules

2015-03-13T01:46:08+00:00

Current approach in handling shadow memory for modules is broken.

Shadow memory could be freed only after memory shadow corresponds it is no
longer used.  vfree() called from interrupt context could use memory its
freeing to store 'struct llist_node' in it:

    void vfree(const void *addr)
    {
    ...
        if (unlikely(in_interrupt())) {
            struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred);
            if (llist_add((struct llist_node *)addr, &p->list))
                    schedule_work(&p->wq);

Later this list node used in free_work() which actually frees memory.
Currently module_memfree() called in interrupt context will free shadow
before freeing module's memory which could provoke kernel crash.

So shadow memory should be freed after module's memory.  However, such
deallocation order could race with kasan_module_alloc() in module_alloc().

Free shadow right before releasing vm area.  At this point vfree()'d
memory is not used anymore and yet not available for other allocations.
New VM_KASAN flag used to indicate that vm area has dynamically allocated
shadow memory so kasan frees shadow only if it was previously allocated.

Signed-off-by: Andrey Ryabinin 
Acked-by: Rusty Russell 
Cc: Dmitry Vyukov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: vmalloc: pass additional vm_flags to __vmalloc_node_range()

2015-02-14T05:21:42+00:00

For instrumenting global variables KASan will shadow memory backing memory
for modules.  So on module loading we will need to allocate memory for
shadow and map it at address in shadow that corresponds to the address
allocated in module_alloc().

__vmalloc_node_range() could be used for this purpose, except it puts a
guard hole after allocated area.  Guard hole in shadow memory should be a
problem because at some future point we might need to have a shadow memory
at address occupied by guard hole.  So we could fail to allocate shadow
for module_alloc().

Now we have VM_NO_GUARD flag disabling guard page, so we need to pass into
__vmalloc_node_range().  Add new parameter 'vm_flags' to
__vmalloc_node_range() function.

Signed-off-by: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Konstantin Serebryany 
Cc: Dmitry Chernenkov 
Signed-off-by: Andrey Konovalov 
Cc: Yuri Gribov 
Cc: Konstantin Khlebnikov 
Cc: Sasha Levin 
Cc: Christoph Lameter 
Cc: Joonsoo Kim 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: vmalloc: add flag preventing guard hole allocation

2015-02-14T05:21:42+00:00

For instrumenting global variables KASan will shadow memory backing memory
for modules.  So on module loading we will need to allocate memory for
shadow and map it at address in shadow that corresponds to the address
allocated in module_alloc().

__vmalloc_node_range() could be used for this purpose, except it puts a
guard hole after allocated area.  Guard hole in shadow memory should be a
problem because at some future point we might need to have a shadow memory
at address occupied by guard hole.  So we could fail to allocate shadow
for module_alloc().

Add a new vm_struct flag 'VM_NO_GUARD' indicating that vm area doesn't
have a guard hole.

Signed-off-by: Andrey Ryabinin 
Cc: Dmitry Vyukov 
Cc: Konstantin Serebryany 
Cc: Dmitry Chernenkov 
Signed-off-by: Andrey Konovalov 
Cc: Yuri Gribov 
Cc: Konstantin Khlebnikov 
Cc: Sasha Levin 
Cc: Christoph Lameter 
Cc: Joonsoo Kim 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/vmalloc.c: clean up map_vm_area third argument

2014-08-07T01:01:19+00:00

Currently map_vm_area() takes (struct page *** pages) as third argument,
and after mapping, it moves (*pages) to point to (*pages +
nr_mappped_pages).

It looks like this kind of increment is useless to its caller these
days.  The callers don't care about the increments and actually they're
trying to avoid this by passing another copy to map_vm_area().

The caller can always guarantee all the pages can be mapped into vm_area
as specified in first argument and the caller only cares about whether
map_vm_area() fails or not.

This patch cleans up the pointer movement in map_vm_area() and updates
its callers accordingly.

Signed-off-by: WANG Chao 
Cc: Zhang Yanfei 
Acked-by: Greg Kroah-Hartman 
Cc: Minchan Kim 
Cc: Nitin Gupta 
Cc: Rusty Russell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/vmalloc.c: rename VM_UNLIST to VM_UNINITIALIZED

2013-07-09T17:33:21+00:00

VM_UNLIST was used to indicate that the vm_struct is not listed in
vmlist.

But after commit 4341fa454796 ("mm, vmalloc: remove list management of
vmlist after initializing vmalloc"), the meaning of this flag changed.
It now means the vm_struct is not fully initialized.  So renaming it to
VM_UNINITIALIZED seems more reasonable.

Also change clear_vm_unlist to clear_vm_uninitialized_flag.

Signed-off-by: Zhang Yanfei 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmalloc: introduce remap_vmalloc_range_partial

2013-07-03T23:07:30+00:00

We want to allocate ELF note segment buffer on the 2nd kernel in vmalloc
space and remap it to user-space in order to reduce the risk that memory
allocation fails on system with huge number of CPUs and so with huge ELF
note segment that exceeds 11-order block size.

Although there's already remap_vmalloc_range for the purpose of
remapping vmalloc memory to user-space, we need to specify user-space
range via vma.
 Mmap on /proc/vmcore needs to remap range across multiple objects, so
the interface that requires vma to cover full range is problematic.

This patch introduces remap_vmalloc_range_partial that receives user-space
range as a pair of base address and size and can be used for mmap on
/proc/vmcore case.

remap_vmalloc_range is rewritten using remap_vmalloc_range_partial.

[akpm@linux-foundation.org: use PAGE_ALIGNED()]
Signed-off-by: HATAYAMA Daisuke 
Cc: KOSAKI Motohiro 
Cc: Vivek Goyal 
Cc: Atsushi Kumagai 
Cc: Lisa Mitchell 
Cc: Zhang Yanfei 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kexec, vmalloc: export additional vmalloc layer information

2013-04-29T22:54:34+00:00

Now, vmap_area_list is exported as VMCOREINFO for makedumpfile to get
the start address of vmalloc region (vmalloc_start).  The address which
contains vmalloc_start value is represented as below:

  vmap_area_list.next - OFFSET(vmap_area.list) + OFFSET(vmap_area.va_start)

However, both OFFSET(vmap_area.va_start) and OFFSET(vmap_area.list)
aren't exported as VMCOREINFO.

So this patch exports them externally with small cleanup.

[akpm@linux-foundation.org: vmalloc.h should include list.h for list_head]
Signed-off-by: Atsushi Kumagai 
Cc: Joonsoo Kim 
Cc: Joonsoo Kim 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Atsushi Kumagai 
Cc: Chris Metcalf 
Cc: Dave Anderson 
Cc: Eric Biederman 
Cc: Guan Xuetao 
Cc: Ingo Molnar 
Cc: Vivek Goyal 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, vmalloc: export vmap_area_list, instead of vmlist

2013-04-29T22:54:34+00:00

Although our intention is to unexport internal structure entirely, but
there is one exception for kexec.  kexec dumps address of vmlist and
makedumpfile uses this information.

We are about to remove vmlist, then another way to retrieve information
of vmalloc layer is needed for makedumpfile.  For this purpose, we
export vmap_area_list, instead of vmlist.

Signed-off-by: Joonsoo Kim 
Signed-off-by: Joonsoo Kim 
Cc: Eric Biederman 
Cc: Dave Anderson 
Cc: Vivek Goyal 
Cc: Atsushi Kumagai 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Chris Metcalf 
Cc: Guan Xuetao 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds