1. 03 May, 2017 38 commits
  2. 27 Apr, 2017 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.9.25 · a8c90ef6
      Greg Kroah-Hartman authored
      a8c90ef6
    • Dan Williams's avatar
      device-dax: switch to srcu, fix rcu_read_lock() vs pte allocation · c36eaa6c
      Dan Williams authored
      commit 956a4cd2 upstream.
      
      The following warning triggers with a new unit test that stresses the
      device-dax interface.
      
       ===============================
       [ ERR: suspicious RCU usage.  ]
       4.11.0-rc4+ #1049 Tainted: G           O
       -------------------------------
       ./include/linux/rcupdate.h:521 Illegal context switch in RCU read-side critical section!
      
       other info that might help us debug this:
      
       rcu_scheduler_active = 2, debug_locks = 0
       2 locks held by fio/9070:
        #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8d0739d7>] __do_page_fault+0x167/0x4f0
        #1:  (rcu_read_lock){......}, at: [<ffffffffc03fbd02>] dax_dev_huge_fault+0x32/0x620 [dax]
      
       Call Trace:
        dump_stack+0x86/0xc3
        lockdep_rcu_suspicious+0xd7/0x110
        ___might_sleep+0xac/0x250
        __might_sleep+0x4a/0x80
        __alloc_pages_nodemask+0x23a/0x360
        alloc_pages_current+0xa1/0x1f0
        pte_alloc_one+0x17/0x80
        __pte_alloc+0x1e/0x120
        __get_locked_pte+0x1bf/0x1d0
        insert_pfn.isra.70+0x3a/0x100
        ? lookup_memtype+0xa6/0xd0
        vm_insert_mixed+0x64/0x90
        dax_dev_huge_fault+0x520/0x620 [dax]
        ? dax_dev_huge_fault+0x32/0x620 [dax]
        dax_dev_fault+0x10/0x20 [dax]
        __do_fault+0x1e/0x140
        __handle_mm_fault+0x9af/0x10d0
        handle_mm_fault+0x16d/0x370
        ? handle_mm_fault+0x47/0x370
        __do_page_fault+0x28c/0x4f0
        trace_do_page_fault+0x58/0x2a0
        do_async_page_fault+0x1a/0xa0
        async_page_fault+0x28/0x30
      
      Inserting a page table entry may trigger an allocation while we are
      holding a read lock to keep the device instance alive for the duration
      of the fault. Use srcu for this keep-alive protection.
      
      Fixes: dee41079 ("/dev/dax, core: file operations and dax-mmap")
      Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c36eaa6c