1. 13 Jun, 2017 1 commit
  2. 19 May, 2017 1 commit
    • Petr Mladek's avatar
      printk: Use the main logbuf in NMI when logbuf_lock is available · 719f6a70
      Petr Mladek authored
      The commit 42a0bb3f ("printk/nmi: generic solution for safe
      printk in NMI") caused that printk stores messages into a temporary
      buffer in NMI context.
      
      The buffer is per-CPU and therefore the size is rather limited.
      It works quite well for NMI backtraces. But there are longer logs
      that might get printed in NMI context, for example, lockdep
      warnings, ftrace_dump_on_oops.
      
      The temporary buffer is used to avoid deadlocks caused by
      logbuf_lock. Also it is needed to avoid races with the other
      temporary buffer that is used when PRINTK_SAFE_CONTEXT is entered.
      But the main buffer can be used in NMI if the lock is available
      and we did not interrupt PRINTK_SAFE_CONTEXT.
      
      The lock is checked using raw_spin_is_locked(). It might cause
      false negatives when the lock is taken on another CPU and
      this CPU is in the safe context from other reasons. Note that
      the safe context is used also to get console semaphore or when
      calling console drivers. For this reason, we do the check in
      printk_nmi_enter(). It makes the handling consistent for
      the entire NMI handler and avoids reshuffling of the messages.
      
      The patch also defines special printk context that allows
      to use printk_deferred() in NMI. Note that we could not flush
      the messages to the consoles because console drivers might use
      many other internal locks.
      
      The newly created vprintk_deferred() disables the preemption
      only around the irq work handling. It is needed there to keep
      the consistency between the two per-CPU variables. But there
      is no reason to disable preemption around vprintk_emit().
      
      Finally, the patch puts back explicit serialization of the NMI
      backtraces from different CPUs. It was removed by the
      commit a9edc880 ("x86/nmi: Perform a safe
      NMI stack trace on all CPUs"). It was not needed because
      the flushing of the temporary per-CPU buffers was serialized.
      
      Link: http://lkml.kernel.org/r/1493912763-24873-1-git-send-email-pmladek@suse.com
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Russell King <rack+kernel@arm.linux.org.uk>
      Cc: Daniel Thompson <daniel.thompson@linaro.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Chris Metcalf <cmetcalf@ezchip.com>
      Cc: x86@kernel.org
      Cc: linux-arm-kernel@lists.infradead.org
      Cc: linux-kernel@vger.kernel.org
      Suggested-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Acked-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
      Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
      719f6a70
  3. 04 May, 2017 2 commits
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk · 9c35baf6
      Linus Torvalds authored
      Pull printk updates from Petr Mladek:
      
       - There is a situation when early console is not deregistered because
         the preferred one matches a wrong entry. It caused messages to appear
         twice.
      
         This is the 2nd attempt to fix it. The first one was wrong, see the
         commit c6c7d83b ('Revert "console: don't prefer first registered
         if DT specifies stdout-path"').
      
         The fix is coupled with some small code clean up. Well, the console
         registration code would deserve a big one. We need to think about it.
      
       - Do not lose information about the preemtive context when the console
         semaphore is re-taken.
      
       - Do not block CPU hotplug when someone else is already pushing
         messages to the console.
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
        printk: fix double printing with earlycon
        printk: rename selected_console -> preferred_console
        printk: fix name/type/scope of preferred_console var
        printk: Correctly handle preemption in console_unlock()
        printk: use console_trylock() in console_cpu_notify()
      9c35baf6
    • Linus Torvalds's avatar
      Merge branch 'akpm' (patches from Andrew) · dd23f273
      Linus Torvalds authored
      Merge misc updates from Andrew Morton:
      
       - a few misc things
      
       - most of MM
      
       - KASAN updates
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (102 commits)
        kasan: separate report parts by empty lines
        kasan: improve double-free report format
        kasan: print page description after stacks
        kasan: improve slab object description
        kasan: change report header
        kasan: simplify address description logic
        kasan: change allocation and freeing stack traces headers
        kasan: unify report headers
        kasan: introduce helper functions for determining bug type
        mm: hwpoison: call shake_page() after try_to_unmap() for mlocked page
        mm: hwpoison: call shake_page() unconditionally
        mm/swapfile.c: fix swap space leak in error path of swap_free_entries()
        mm/gup.c: fix access_ok() argument type
        mm/truncate: avoid pointless cleancache_invalidate_inode() calls.
        mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty
        fs/block_dev: always invalidate cleancache in invalidate_bdev()
        fs: fix data invalidation in the cleancache during direct IO
        zram: reduce load operation in page_same_filled
        zram: use zram_free_page instead of open-coded
        zram: introduce zram data accessor
        ...
      dd23f273
  4. 03 May, 2017 36 commits