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  1. 24 6月, 2008 4 次提交
    • N
      mm: fix race in COW logic · 945754a1
      由 Nick Piggin 提交于 
      There is a race in the COW logic.  It contains a shortcut to avoid the
COW and reuse the page if we have the sole reference on the page,
however it is possible to have two racing do_wp_page()ers with one
causing the other to mistakenly believe it is safe to take the shortcut
when it is not.  This could lead to data corruption.

Process 1 and process2 each have a wp pte of the same anon page (ie.
one forked the other).  The page's mapcount is 2.  Then they both
attempt to write to it around the same time...

  proc1				proc2 thr1			proc2 thr2
  CPU0				CPU1				CPU3
  do_wp_page()			do_wp_page()
				 trylock_page()
				  can_share_swap_page()
				   load page mapcount (==2)
				  reuse = 0
				 pte unlock
				 copy page to new_page
				 pte lock
				 page_remove_rmap(page);
   trylock_page()
    can_share_swap_page()
     load page mapcount (==1)
    reuse = 1
   ptep_set_access_flags (allow W)

  write private key into page
								read from page
				ptep_clear_flush()
				set_pte_at(pte of new_page)

Fix this by moving the page_remove_rmap of the old page after the pte
clear and flush.  Potentially the entire branch could be moved down
here, but in order to stay consistent, I won't (should probably move all
the *_mm_counter stuff with one patch).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NHugh Dickins <hugh@veritas.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      945754a1
    • L
      Fix ZERO_PAGE breakage with vmware · 672ca28e
      由 Linus Torvalds 提交于 
      Commit 89f5b7da ("Reinstate ZERO_PAGE
optimization in 'get_user_pages()' and fix XIP") broke vmware, as
reported by Jeff Chua:

  "This broke vmware 6.0.4.
   Jun 22 14:53:03.845: vmx| NOT_IMPLEMENTED
   /build/mts/release/bora-93057/bora/vmx/main/vmmonPosix.c:774"

and the reason seems to be that there's an old bug in how we handle do
FOLL_ANON on VM_SHARED areas in get_user_pages(), but since it only
triggered if the whole page table was missing, nobody had apparently hit
it before.

The recent changes to 'follow_page()' made the FOLL_ANON logic trigger
not just for whole missing page tables, but for individual pages as
well, and exposed this problem.

This fixes it by making the test for when FOLL_ANON is used more
careful, and also makes the code easier to read and understand by moving
the logic to a separate inline function.
Reported-and-tested-by: NJeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      672ca28e
    • G
      removed unused var real_tty on n_tty_ioctl() · 96a331b1
      由 Gustavo Fernando Padovan 提交于 
      I noted that the 'struct tty_struct *real_tty' is not used in this
function, so I removed the code about 'real_tty'.
Signed-off-by: NGustavo Fernando Padovan <gustavo@las.ic.unicamp.br>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      96a331b1
    • A
      tty_driver: Update required method documentation · 36c7343b
      由 Alan Cox 提交于 
      Some of the requirement rules are now more relaxed. Also correct a
contradiction in the previous update
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      36c7343b
  3. 23 6月, 2008 1 次提交
  5. 22 6月, 2008 4 次提交
  7. 21 6月, 2008 29 次提交
  9. 20 6月, 2008 2 次提交