Mahesh Salgaonkar 75ecfb4951 powerpc/mce: Fix a bug where mce loops on memory UE.
The current code extracts the physical address for UE errors and then
hooks it up into memory failure infrastructure. On successful
extraction of physical address it wrongly sets "handled = 1" which
means this UE error has been recovered. Since MCE handler gets return
value as handled = 1, it assumes that error has been recovered and
goes back to same NIP. This causes MCE interrupt again and again in a
loop leading to hard lockup.

Also, initialize phys_addr to ULONG_MAX so that we don't end up
queuing undesired page to hwpoison.

Without this patch we see:
  Severe Machine check interrupt [Recovered]
    NIP: [000000001002588c] PID: 7109 Comm: find
    Initiator: CPU
    Error type: UE [Load/Store]
      Effective address: 00007fffd2755940
      Physical address:  000020181a080000
  ...
  Severe Machine check interrupt [Recovered]
    NIP: [000000001002588c] PID: 7109 Comm: find
    Initiator: CPU
    Error type: UE [Load/Store]
      Effective address: 00007fffd2755940
      Physical address:  000020181a080000
  Severe Machine check interrupt [Recovered]
    NIP: [000000001002588c] PID: 7109 Comm: find
    Initiator: CPU
    Error type: UE [Load/Store]
      Effective address: 00007fffd2755940
      Physical address:  000020181a080000
  Memory failure: 0x20181a08: recovery action for dirty LRU page: Recovered
  Memory failure: 0x20181a08: already hardware poisoned
  Memory failure: 0x20181a08: already hardware poisoned
  Memory failure: 0x20181a08: already hardware poisoned
  Memory failure: 0x20181a08: already hardware poisoned
  Memory failure: 0x20181a08: already hardware poisoned
  Memory failure: 0x20181a08: already hardware poisoned
  ...
  Watchdog CPU:38 Hard LOCKUP

After this patch we see:

  Severe Machine check interrupt [Not recovered]
    NIP: [00007fffaae585f4] PID: 7168 Comm: find
    Initiator: CPU
    Error type: UE [Load/Store]
      Effective address: 00007fffaafe28ac
      Physical address:  00002017c0bd0000
  find[7168]: unhandled signal 7 at 00007fffaae585f4 nip 00007fffaae585f4 lr 00007fffaae585e0 code 4
  Memory failure: 0x2017c0bd: recovery action for dirty LRU page: Recovered

Fixes: 01eaac2b05 ("powerpc/mce: Hookup ierror (instruction) UE errors")
Fixes: ba41e1e1cc ("powerpc/mce: Hookup derror (load/store) UE errors")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-04-24 13:54:51 +10:00
2018-01-06 10:59:44 -07:00
2018-04-22 19:20:09 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Description
No description provided
Readme 3.4 GiB
Languages
C 97%
Assembly 1%
Shell 0.6%
Rust 0.5%
Python 0.4%
Other 0.3%