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  1. May 02, 2013
  3. May 01, 2013
    • Dmitry Torokhov's avatar
      Merge branch 'next' into for-linus · bf61c884
      Dmitry Torokhov authored 
      Prepare first set of updates for 3.10 merge window.
      bf61c884
    • Linus Torvalds's avatar
      Merge branch 'ipc-scalability' · 823e75f7
      Linus Torvalds authored 
      Merge IPC cleanup and scalability patches from Andrew Morton.

This cleans up many of the oddities in the IPC code, uses the list
iterator helpers, splits out locking and adds per-semaphore locks for
greater scalability of the IPC semaphore code.

Most normal user-level locking by now uses futexes (ie pthreads, but
also a lot of specialized locks), but SysV IPC semaphores are apparently
still used in some big applications, either for portability reasons, or
because they offer tracking and undo (and you don't need to have a
special shared memory area for them).

Our IPC semaphore scalability was pitiful.  We used to lock much too big
ranges, and we used to have a single ipc lock per ipc semaphore array.
Most loads never cared, but some do.  There are some numbers in the
individual commits.

* ipc-scalability:
  ipc: sysv shared memory limited to 8TiB
  ipc/msg.c: use list_for_each_entry_[safe] for list traversing
  ipc,sem: fine grained locking for semtimedop
  ipc,sem: have only one list in struct sem_queue
  ipc,sem: open code and rename sem_lock
  ipc,sem: do not hold ipc lock more than necessary
  ipc: introduce lockless pre_down ipcctl
  ipc: introduce obtaining a lockless ipc object
  ipc: remove bogus lock comment for ipc_checkid
  ipc/msgutil.c: use linux/uaccess.h
  ipc: refactor msg list search into separate function
  ipc: simplify msg list search
  ipc: implement MSG_COPY as a new receive mode
  ipc: remove msg handling from queue scan
  ipc: set EFAULT as default error in load_msg()
  ipc: tighten msg copy loops
  ipc: separate msg allocation from userspace copy
  ipc: clamp with min()
      823e75f7
    • Robin Holt's avatar
      ipc: sysv shared memory limited to 8TiB · d69f3bad
      Robin Holt authored 
      

Trying to run an application which was trying to put data into half of
memory using shmget(), we found that having a shmall value below 8EiB-8TiB
would prevent us from using anything more than 8TiB.  By setting
kernel.shmall greater than 8EiB-8TiB would make the job work.

In the newseg() function, ns->shm_tot which, at 8TiB is INT_MAX.

ipc/shm.c:
 458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 459 {
...
 465         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
...
 474         if (ns->shm_tot + numpages > ns->shm_ctlall)
 475                 return -ENOSPC;

[akpm@linux-foundation.org: make ipc/shm.c:newseg()'s numpages size_t, not int]
Signed-off-by: default avatarRobin Holt <holt@sgi.com>
Reported-by: default avatarAlex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d69f3bad
    • Nikola Pajkovsky's avatar
      ipc/msg.c: use list_for_each_entry_[safe] for list traversing · 41239fe8
      Nikola Pajkovsky authored 
      

The ipc/msg.c code does its list operations by hand and it open-codes the
accesses, instead of using for_each_entry_[safe].

Signed-off-by: default avatarNikola Pajkovsky <npajkovs@redhat.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      41239fe8