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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-05-24 17:11:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-25 08:39:12 -0700
commitd16dfc550f5326a4000f3322582a7c05dec91d7a (patch)
tree8ee963542705cbf2187777f1d3f2b209cbda827a /fs/exec.c
parentd05f3169c0fbca16132ec7c2be71685c6de638b5 (diff)
downloadop-kernel-dev-d16dfc550f5326a4000f3322582a7c05dec91d7a.zip
op-kernel-dev-d16dfc550f5326a4000f3322582a7c05dec91d7a.tar.gz
mm: mmu_gather rework
Rework the existing mmu_gather infrastructure. The direct purpose of these patches was to allow preemptible mmu_gather, but even without that I think these patches provide an improvement to the status quo. The first 9 patches rework the mmu_gather infrastructure. For review purpose I've split them into generic and per-arch patches with the last of those a generic cleanup. The next patch provides generic RCU page-table freeing, and the followup is a patch converting s390 to use this. I've also got 4 patches from DaveM lined up (not included in this series) that uses this to implement gup_fast() for sparc64. Then there is one patch that extends the generic mmu_gather batching. After that follow the mm preemptibility patches, these make part of the mm a lot more preemptible. It converts i_mmap_lock and anon_vma->lock to mutexes which together with the mmu_gather rework makes mmu_gather preemptible as well. Making i_mmap_lock a mutex also enables a clean-up of the truncate code. This also allows for preemptible mmu_notifiers, something that XPMEM I think wants. Furthermore, it removes the new and universially detested unmap_mutex. This patch: Remove the first obstacle towards a fully preemptible mmu_gather. The current scheme assumes mmu_gather is always done with preemption disabled and uses per-cpu storage for the page batches. Change this to try and allocate a page for batching and in case of failure, use a small on-stack array to make some progress. Preemptible mmu_gather is desired in general and usable once i_mmap_lock becomes a mutex. Doing it before the mutex conversion saves us from having to rework the code by moving the mmu_gather bits inside the pte_lock. Also avoid flushing the tlb batches from under the pte lock, this is useful even without the i_mmap_lock conversion as it significantly reduces pte lock hold times. [akpm@linux-foundation.org: fix comment tpyo] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/fs/exec.c b/fs/exec.c
index e276d5e..936f577 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -600,7 +600,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
unsigned long length = old_end - old_start;
unsigned long new_start = old_start - shift;
unsigned long new_end = old_end - shift;
- struct mmu_gather *tlb;
+ struct mmu_gather tlb;
BUG_ON(new_start > new_end);
@@ -626,12 +626,12 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
return -ENOMEM;
lru_add_drain();
- tlb = tlb_gather_mmu(mm, 0);
+ tlb_gather_mmu(&tlb, mm, 0);
if (new_end > old_start) {
/*
* when the old and new regions overlap clear from new_end.
*/
- free_pgd_range(tlb, new_end, old_end, new_end,
+ free_pgd_range(&tlb, new_end, old_end, new_end,
vma->vm_next ? vma->vm_next->vm_start : 0);
} else {
/*
@@ -640,10 +640,10 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
* have constraints on va-space that make this illegal (IA64) -
* for the others its just a little faster.
*/
- free_pgd_range(tlb, old_start, old_end, new_end,
+ free_pgd_range(&tlb, old_start, old_end, new_end,
vma->vm_next ? vma->vm_next->vm_start : 0);
}
- tlb_finish_mmu(tlb, new_end, old_end);
+ tlb_finish_mmu(&tlb, new_end, old_end);
/*
* Shrink the vma to just the new range. Always succeeds.
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