1. 11 Jan, 2003 8 commits
    • Andrew Morton's avatar
      [PATCH] misc fixes · 0c682373
      Andrew Morton authored
      - Fix error-path mem leak in __vfs_follow_link() (From a recent AC->2.4
        patch)
      
      - Make drivers/net/aironet4500_proc.c:driver_lock static.
      0c682373
    • Andrew Morton's avatar
      [PATCH] Fix an SMP+preempt latency problem · 2faf4338
      Andrew Morton authored
      Here is spin_lock():
      
      #define spin_lock(lock) \
      do { \
              preempt_disable(); \
              _raw_spin_lock(lock); \
      } while(0)
      
      
      Here is the scenario:
      
      CPU0:
      	spin_lock(some_lock);
      	do_very_long_thing();	/* This has cond_resched()s in it */
      
      CPU1:
      	spin_lock(some_lock);
      
      Now suppose that the scheduler tries to schedule a task on CPU1.  Nothing
      happens, because CPU1 is spinning on the lock with preemption disabled.  CPU0
      will happliy hold the lock for a long time because nobody has set
      need_resched() against CPU0.
      
      This problem can cause scheduling latencies of many tens of milliseconds on
      SMP on kernels which handle UP quite happily.
      
      
      This patch fixes the problem by changing the spin_lock() and write_lock()
      contended slowpath to spin on the lock by hand, while polling for preemption
      requests.
      
      I would have done read_lock() too, but we don't seem to have read_trylock()
      primitives.
      
      The patch also shrinks the kernel by 30k due to not having separate
      out-of-line spinning code for each spin_lock() callsite.
      2faf4338
    • Andrew Morton's avatar
      [PATCH] low-latency pagetable teardown · b4adddd6
      Andrew Morton authored
      Pagetable teardown can hold page_table_lock for extremely long periods -
      hundreds of milliseconds.  This is pretty much the final source of high
      scheduling latency in the core kernel.
      
      We fixed it for zap_page_range() by chunking the work up and dropping the
      lock occasionally if needed.  But that did not fix exit_mmap() and
      unmap_region().
      
      So what this patch does is to create an uber-zapper "unmap_vmas()" which
      provides all the vma-walking, page unmapping and low-latency lock-dropping
      which zap_page_range(), exit_mmap() and unmap_region() require.  Those three
      functions are updated to call unmap_vmas().
      
      It's actually a bit of a cleanup...
      b4adddd6
    • Andrew Morton's avatar
      [PATCH] Don't reverse the VMA list in touched_by_munmap() · 670fe925
      Andrew Morton authored
      touched_by_munmap() returns a reversed list of VMA's.  That makes things
      harder in the low-latency-page-zapping patch.
      
      So change touched_by_munmap() to return a VMA list which is in the original
      order - ascending virtual addresses.
      
      Oh, and rename it to <hugh>detach_vmas_to_be_unmapped()</hugh>.  It now
      returns nothing, because we know that the VMA we passed in is the head of the
      to-be-unmapped list.
      670fe925
    • Andrew Morton's avatar
      [PATCH] replace `typedef mmu_gather_t' with `struct mmu_gather' · 0c17b328
      Andrew Morton authored
      In the next patch I wish to add to mm.h prototypes of functions which take an
      mmu_gather_t* argument.   To do this I must either:
      
      a) include tlb.h in mm.h
      
         Not good - more nested includes when a simple forward decl is sufficient.
      
      b) Add `typedef struct free_pte_ctx mmu_gather_t;' to mm.h.
      
         That's silly - it's supposed to be an opaque type.
      
         or
      
      c) Remove the pesky typedef.
      
         Bingo.
      0c17b328
    • Andrew Morton's avatar
      [PATCH] simplify and generalise cond_resched_lock · ab706391
      Andrew Morton authored
      cond_resched_lock() _used_ to be "if this is the only lock which I am holding
      then drop it and schedule if needed".
      
      However with the i_shared_lock->i_shared_sem change, neither of its two
      callsites now need those semantics.  So this patch changes it to mean just
      "if needed, drop this lock and reschedule".
      
      This allows us to also schedule if CONFIG_PREEMPT=n, which is useful -
      zap_page_range() can run for an awfully long time.
      
      The preempt and non-preempt versions of cond_resched_lock() have been
      unified.
      ab706391
    • Andrew Morton's avatar
      [PATCH] turn i_shared_lock into a semaphore · d9be9136
      Andrew Morton authored
      i_shared_lock is held for a very long time during vmtruncate() and causes
      high scheduling latencies when truncating a file which is mmapped.  I've seen
      100 milliseconds.
      
      So turn it into a semaphore.  It nests inside mmap_sem.
      
      This change is also needed by the shared pagetable patch, which needs to
      unshare pte's on the vmtruncate path - lots of pagetable pages need to
      be allocated and they are using __GFP_WAIT.
      
      The patch also makes unmap_vma() static.
      d9be9136
    • Ingo Molnar's avatar
      [PATCH] ptrace-fix-2.5.56-A0 · b473e48b
      Ingo Molnar authored
      This patch from Roland McGrath fixes a threading related ptrace bug:
      PTRACE_ATTACH should not stop everybody for each thread attached.
      b473e48b
  2. 10 Jan, 2003 32 commits