1. 27 Apr, 2012 38 commits
  2. 22 Apr, 2012 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.0.29 · 41f45f5e
      Greg Kroah-Hartman authored
      41f45f5e
    • Martin Schwidefsky's avatar
      S390: fix tlb flushing for page table pages · a741ac8b
      Martin Schwidefsky authored
      commit cd94154c upstream.
      
      Git commit 36409f63 "use generic RCU
      page-table freeing code" introduced a tlb flushing bug. Partially revert
      the above git commit and go back to s390 specific page table flush code.
      
      For s390 the TLB can contain three types of entries, "normal" TLB
      page-table entries, TLB combined region-and-segment-table (CRST) entries
      and real-space entries. Linux does not use real-space entries which
      leaves normal TLB entries and CRST entries. The CRST entries are
      intermediate steps in the page-table translation called translation paths.
      For example a 4K page access in a three-level page table setup will
      create two CRST TLB entries and one page-table TLB entry. The advantage
      of that approach is that a page access next to the previous one can reuse
      the CRST entries and needs just a single read from memory to create the
      page-table TLB entry. The disadvantage is that the TLB flushing rules are
      more complicated, before any page-table may be freed the TLB needs to be
      flushed. 
      
      In short: the generic RCU page-table freeing code is incorrect for the
      CRST entries, in particular the check for mm_users < 2 is troublesome.
      
      This is applicable to 3.0+ kernels.
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a741ac8b