linux-toradex.git/arch/tile/mm, branch v3.10.76

vm: add VM_FAULT_SIGSEGV handling support

2015-04-29T08:34:00+00:00

commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream.

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai 
Tested-by: Jan Engelhardt 
Acked-by: Heiko Carstens  # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds 
[shengyong: Backport to 3.10
 - adjust context
 - ignore modification for arch nios2, because 3.10 does not support it
 - ignore modification for driver lustre, because 3.10 does not support it
 - ignore VM_FAULT_FALLBACK in VM_FAULT_ERROR, becase 3.10 does not support
   this flag
 - add SIGSEGV handling to powerpc/cell spu_fault.c, because 3.10 does not
   separate it to copro_fault.c
 - add SIGSEGV handling in mm/memory.c, because 3.10 does not separate it
   to gup.c
]
Signed-off-by: Sheng Yong 
Signed-off-by: Greg Kroah-Hartman

arch: mm: pass userspace fault flag to generic fault handler

2014-11-21T17:22:56+00:00

commit 759496ba6407c6994d6a5ce3a5e74937d7816208 upstream.

Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Cc: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Cc: azurIt 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Cong Wang 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

arch: mm: remove obsolete init OOM protection

2014-11-21T17:22:55+00:00

commit 94bce453c78996cc4373d5da6cfabe07fcc6d9f9 upstream.

The memcg code can trap tasks in the context of the failing allocation
until an OOM situation is resolved.  They can hold all kinds of locks
(fs, mm) at this point, which makes it prone to deadlocking.

This series converts memcg OOM handling into a two step process that is
started in the charge context, but any waiting is done after the fault
stack is fully unwound.

Patches 1-4 prepare architecture handlers to support the new memcg
requirements, but in doing so they also remove old cruft and unify
out-of-memory behavior across architectures.

Patch 5 disables the memcg OOM handling for syscalls, readahead, kernel
faults, because they can gracefully unwind the stack with -ENOMEM.  OOM
handling is restricted to user triggered faults that have no other
option.

Patch 6 reworks memcg's hierarchical OOM locking to make it a little
more obvious wth is going on in there: reduce locked regions, rename
locking functions, reorder and document.

Patch 7 implements the two-part OOM handling such that tasks are never
trapped with the full charge stack in an OOM situation.

This patch:

Back before smart OOM killing, when faulting tasks were killed directly on
allocation failures, the arch-specific fault handlers needed special
protection for the init process.

Now that all fault handlers call into the generic OOM killer (see commit
609838cfed97: "mm: invoke oom-killer from remaining unconverted page
fault handlers"), which already provides init protection, the
arch-specific leftovers can be removed.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Acked-by: KOSAKI Motohiro 
Cc: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Cc: azurIt 
Acked-by: Vineet Gupta 	[arch/arc bits]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Cong Wang 
Signed-off-by: Greg Kroah-Hartman

mm: invoke oom-killer from remaining unconverted page fault handlers

2014-11-21T17:22:55+00:00

commit 609838cfed972d49a65aac7923a9ff5cbe482e30 upstream.

A few remaining architectures directly kill the page faulting task in an
out of memory situation.  This is usually not a good idea since that
task might not even use a significant amount of memory and so may not be
the optimal victim to resolve the situation.

Since 2.6.29's 1c0fe6e ("mm: invoke oom-killer from page fault") there
is a hook that architecture page fault handlers are supposed to call to
invoke the OOM killer and let it pick the right task to kill.  Convert
the remaining architectures over to this hook.

To have the previous behavior of simply taking out the faulting task the
vm.oom_kill_allocating_task sysctl can be set to 1.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Cc: KAMEZAWA Hiroyuki 
Acked-by: David Rientjes 
Acked-by: Vineet Gupta    [arch/arc bits]
Cc: James Hogan 
Cc: David Howells 
Cc: Jonas Bonn 
Cc: Chen Liqin 
Cc: Lennox Wu 
Cc: Chris Metcalf 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Cong Wang 
Signed-off-by: Greg Kroah-Hartman

mm, vmalloc: change iterating a vmlist to find_vm_area()

2013-04-29T22:54:33+00:00

This patchset removes vm_struct list management after initializing
vmalloc.  Adding and removing an entry to vmlist is linear time
complexity, so it is inefficient.  If we maintain this list, overall
time complexity of adding and removing area to vmalloc space is O(N),
although we use rbtree for finding vacant place and it's time complexity
is just O(logN).

And vmlist and vmlist_lock is used many places of outside of vmalloc.c.
It is preferable that we hide this raw data structure and provide
well-defined function for supporting them, because it makes that they
cannot mistake when manipulating theses structure and it makes us easily
maintain vmalloc layer.

For kexec and makedumpfile, I export vmap_area_list, instead of vmlist.
This comes from Atsushi's recommendation.  For more information, please
refer below link.  https://lkml.org/lkml/2012/12/6/184

This patch:

The purpose of iterating a vmlist is finding vm area with specific virtual
address.  find_vm_area() is provided for this purpose and more efficient,
because it uses a rbtree.  So change it.

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

swap: add per-partition lock for swapfile

2013-02-24T01:50:17+00:00

swap_lock is heavily contended when I test swap to 3 fast SSD (even
slightly slower than swap to 2 such SSD).  The main contention comes
from swap_info_get().  This patch tries to fix the gap with adding a new
per-partition lock.

Global data like nr_swapfiles, total_swap_pages, least_priority and
swap_list are still protected by swap_lock.

nr_swap_pages is an atomic now, it can be changed without swap_lock.  In
theory, it's possible get_swap_page() finds no swap pages but actually
there are free swap pages.  But sounds not a big problem.

Accessing partition specific data (like scan_swap_map and so on) is only
protected by swap_info_struct.lock.

Changing swap_info_struct.flags need hold swap_lock and
swap_info_struct.lock, because scan_scan_map() will check it.  read the
flags is ok with either the locks hold.

If both swap_lock and swap_info_struct.lock must be hold, we always hold
the former first to avoid deadlock.

swap_entry_free() can change swap_list.  To delete that code, we add a
new highest_priority_index.  Whenever get_swap_page() is called, we
check it.  If it's valid, we use it.

It's a pity get_swap_page() still holds swap_lock().  But in practice,
swap_lock() isn't heavily contended in my test with this patch (or I can
say there are other much more heavier bottlenecks like TLB flush).  And
BTW, looks get_swap_page() doesn't really need the lock.  We never free
swap_info[] and we check SWAP_WRITEOK flag.  The only risk without the
lock is we could swapout to some low priority swap, but we can quickly
recover after several rounds of swap, so sounds not a big deal to me.
But I'd prefer to fix this if it's a real problem.

"swap: make each swap partition have one address_space" improved the
swapout speed from 1.7G/s to 2G/s.  This patch further improves the
speed to 2.3G/s, so around 15% improvement.  It's a multi-process test,
so TLB flush isn't the biggest bottleneck before the patches.

[arnd@arndb.de: fix it for nommu]
[hughd@google.com: add missing unlock]
[minchan@kernel.org: get rid of lockdep whinge on sys_swapon]
Signed-off-by: Shaohua Li 
Cc: Hugh Dickins 
Cc: Rik van Riel 
Cc: Minchan Kim 
Cc: Greg Kroah-Hartman 
Cc: Seth Jennings 
Cc: Konrad Rzeszutek Wilk 
Cc: Xiao Guangrong 
Cc: Dan Magenheimer 
Cc: Stephen Rothwell 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Hugh Dickins 
Signed-off-by: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory-hotplug: introduce new arch_remove_memory() for removing page table

2013-02-24T01:50:12+00:00

For removing memory, we need to remove page tables.  But it depends on
architecture.  So the patch introduce arch_remove_memory() for removing
page table.  Now it only calls __remove_pages().

Note: __remove_pages() for some archtecuture is not implemented
      (I don't know how to implement it for s390).

Signed-off-by: Wen Congyang 
Signed-off-by: Tang Chen 
Acked-by: KAMEZAWA Hiroyuki 
Cc: KOSAKI Motohiro 
Cc: Jiang Liu 
Cc: Jianguo Wu 
Cc: Kamezawa Hiroyuki 
Cc: Lai Jiangshan 
Cc: Wu Jianguo 
Cc: Yasuaki Ishimatsu 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove flags argument to mmap_region

2013-02-24T01:50:11+00:00

After the MAP_POPULATE handling has been moved to mmap_region() call
sites, the only remaining use of the flags argument is to pass the
MAP_NORESERVE flag.  This can be just as easily handled by
do_mmap_pgoff(), so do that and remove the mmap_region() flags
parameter.

[akpm@linux-foundation.org: remove double parens]
Signed-off-by: Michel Lespinasse 
Acked-by: Rik van Riel 
Tested-by: Andy Lutomirski 
Cc: Greg Ungerer 
Cc: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

tile: export a handful of symbols appropriately

2013-02-08T18:20:36+00:00

This was shown up by running with "allmodconfig".  I used
EXPORT_SYMBOL() to match existing conventions in files that
were already exporting symbols, or that were exported that way
by other architectures, and otherwise EXPORT_SYMBOL_GPL().

Signed-off-by: Chris Metcalf

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

2012-12-12T20:22:13+00:00

Pull big execve/kernel_thread/fork unification series from Al Viro:
 "All architectures are converted to new model.  Quite a bit of that
  stuff is actually shared with architecture trees; in such cases it's
  literally shared branch pulled by both, not a cherry-pick.

  A lot of ugliness and black magic is gone (-3KLoC total in this one):

   - kernel_thread()/kernel_execve()/sys_execve() redesign.

     We don't do syscalls from kernel anymore for either kernel_thread()
     or kernel_execve():

     kernel_thread() is essentially clone(2) with callback run before we
     return to userland, the callbacks either never return or do
     successful do_execve() before returning.

     kernel_execve() is a wrapper for do_execve() - it doesn't need to
     do transition to user mode anymore.

     As a result kernel_thread() and kernel_execve() are
     arch-independent now - they live in kernel/fork.c and fs/exec.c
     resp.  sys_execve() is also in fs/exec.c and it's completely
     architecture-independent.

   - daemonize() is gone, along with its parts in fs/*.c

   - struct pt_regs * is no longer passed to do_fork/copy_process/
     copy_thread/do_execve/search_binary_handler/->load_binary/do_coredump.

   - sys_fork()/sys_vfork()/sys_clone() unified; some architectures
     still need wrappers (ones with callee-saved registers not saved in
     pt_regs on syscall entry), but the main part of those suckers is in
     kernel/fork.c now."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (113 commits)
  do_coredump(): get rid of pt_regs argument
  print_fatal_signal(): get rid of pt_regs argument
  ptrace_signal(): get rid of unused arguments
  get rid of ptrace_signal_deliver() arguments
  new helper: signal_pt_regs()
  unify default ptrace_signal_deliver
  flagday: kill pt_regs argument of do_fork()
  death to idle_regs()
  don't pass regs to copy_process()
  flagday: don't pass regs to copy_thread()
  bfin: switch to generic vfork, get rid of pointless wrappers
  xtensa: switch to generic clone()
  openrisc: switch to use of generic fork and clone
  unicore32: switch to generic clone(2)
  score: switch to generic fork/vfork/clone
  c6x: sanitize copy_thread(), get rid of clone(2) wrapper, switch to generic clone()
  take sys_fork/sys_vfork/sys_clone prototypes to linux/syscalls.h
  mn10300: switch to generic fork/vfork/clone
  h8300: switch to generic fork/vfork/clone
  tile: switch to generic clone()
  ...

Conflicts:
	arch/microblaze/include/asm/Kbuild