1. 12 Jan, 2006 1 commit
  2. 11 Jan, 2006 1 commit
  3. 09 Jan, 2006 2 commits
  4. 06 Jan, 2006 1 commit
  5. 07 Nov, 2005 1 commit
  6. 30 Oct, 2005 4 commits
    • Hugh Dickins's avatar
      [PATCH] mm: split page table lock · 4c21e2f2
      Hugh Dickins authored
      
      
      Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
      a many-threaded application which concurrently initializes different parts of
      a large anonymous area.
      
      This patch corrects that, by using a separate spinlock per page table page, to
      guard the page table entries in that page, instead of using the mm's single
      page_table_lock.  (But even then, page_table_lock is still used to guard page
      table allocation, and anon_vma allocation.)
      
      In this implementation, the spinlock is tucked inside the struct page of the
      page table page: with a BUILD_BUG_ON in case it overflows - which it would in
      the case of 32-bit PA-RISC with spinlock debugging enabled.
      
      Splitting the lock is not quite for free: another cacheline access.  Ideally,
      I suppose we would use split ptlock only for multi-threaded processes on
      multi-cpu machines; but deciding that dynamically would have its own costs.
      So for now enable it by config, at some number of cpus - since the Kconfig
      language doesn't support inequalities, let preprocessor compare that with
      NR_CPUS.  But I don't think it's worth being user-configurable: for good
      testing of both split and unsplit configs, split now at 4 cpus, and perhaps
      change that to 8 later.
      
      There is a benefit even for singly threaded processes: kswapd can be attacking
      one part of the mm while another part is busy faulting.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4c21e2f2
    • Hugh Dickins's avatar
      [PATCH] mm: pte_offset_map_lock loops · 705e87c0
      Hugh Dickins authored
      
      
      Convert those common loops using page_table_lock on the outside and
      pte_offset_map within to use just pte_offset_map_lock within instead.
      
      These all hold mmap_sem (some exclusively, some not), so at no level can a
      page table be whipped away from beneath them.  But whereas pte_alloc loops
      tested with the "atomic" pmd_present, these loops are testing with pmd_none,
      which on i386 PAE tests both lower and upper halves.
      
      That's now unsafe, so add a cast into pmd_none to test only the vital lower
      half: we lose a little sensitivity to a corrupt middle directory, but not
      enough to worry about.  It appears that i386 and UML were the only
      architectures vulnerable in this way, and pgd and pud no problem.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      705e87c0
    • Hugh Dickins's avatar
      [PATCH] mm: rss = file_rss + anon_rss · 4294621f
      Hugh Dickins authored
      
      
      I was lazy when we added anon_rss, and chose to change as few places as
      possible.  So currently each anonymous page has to be counted twice, in rss
      and in anon_rss.  Which won't be so good if those are atomic counts in some
      configurations.
      
      Change that around: keep file_rss and anon_rss separately, and add them
      together (with get_mm_rss macro) when the total is needed - reading two
      atomics is much cheaper than updating two atomics.  And update anon_rss
      upfront, typically in memory.c, not tucked away in page_add_anon_rmap.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4294621f
    • Hugh Dickins's avatar
      [PATCH] mm: anon is already wrprotected · 72866f6f
      Hugh Dickins authored
      
      
      do_anonymous_page's pte_wrprotect causes some confusion: in such a case,
      vm_page_prot must already be forcing COW, so must omit write permission, and
      so the pte_wrprotect is redundant.  Replace it by a comment to that effect,
      and reword the comment on unuse_pte which also caused confusion.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      72866f6f
  7. 23 Sep, 2005 1 commit
    • Rob Landley's avatar
      [PATCH] Fix bd_claim() error code. · f7b3a435
      Rob Landley authored
      
      
      Problem: In some circumstances, bd_claim() is returning the wrong error
      code.
      
      If we try to swapon an unused block device that isn't swap formatted, we
      get -EINVAL.  But if that same block device is already mounted, we instead
      get -EBUSY, even though it still isn't a valid swap device.
      
      This issue came up on the busybox list trying to get the error message
      from "swapon -a" right.  If a swap device is already enabled, we get -EBUSY,
      and we shouldn't report this as an error.  But we can't distinguish the two
      -EBUSY conditions, which are very different errors.
      
      In the code, bd_claim() returns either 0 or -EBUSY, but in this case busy
      means "somebody other than sys_swapon has already claimed this", and
      _that_ means this block device can't be a valid swap device.  So return
      -EINVAL there.
      Signed-off-by: default avatarRob Landley <rob@landley.net>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      f7b3a435
  8. 10 Sep, 2005 1 commit
  9. 05 Sep, 2005 12 commits
  10. 22 Jun, 2005 1 commit
    • Hugh Dickins's avatar
      [PATCH] can_share_swap_page: use page_mapcount · c475a8ab
      Hugh Dickins authored
      
      
      Remember that ironic get_user_pages race?  when the raised page_count on a
      page swapped out led do_wp_page to decide that it had to copy on write, so
      substituted a different page into userspace.  2.6.7 onwards have Andrea's
      solution, where try_to_unmap_one backs out if it finds page_count raised.
      
      Which works, but is unsatisfying (rmap.c has no other page_count heuristics),
      and was found a few months ago to hang an intensive page migration test.  A
      year ago I was hesitant to engage page_mapcount, now it seems the right fix.
      
      So remove the page_count hack from try_to_unmap_one; and use activate_page in
      unuse_mm when dropping lock, to replace its secondary effect of helping
      swapoff to make progress in that case.
      
      Simplify can_share_swap_page (now called only on anonymous pages) to check
      page_mapcount + page_swapcount == 1: still needs the page lock to stabilize
      their (pessimistic) sum, but does not need swapper_space.tree_lock for that.
      
      In do_swap_page, move swap_free and unlock_page below page_add_anon_rmap, to
      keep sum on the high side, and correct when can_share_swap_page called.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c475a8ab
  11. 17 May, 2005 1 commit
  12. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4