On Fri, May 17, 2019 at 10:18:02AM +0530, Anshuman Khandual wrote:
>
>
> On 05/17/2019 09:38 AM, Jane Chu wrote:
> > Some user who install SIGBUS handler that does longjmp out
>
> What the longjmp about ? Are you referring to the mechanism of catching the
> signal which was registered ?
AFAIK, longjmp() might be useful for signal-based retrying, so highly
optimized applications like Oracle DB might want to utilize it to handle
memory errors in application level, I guess.
>
> > therefore keeping the process alive is confused by the error
> > message
> > "[188988.765862] Memory failure: 0x1840200: Killing
> > cellsrv:33395 due to hardware memory corruption"
>
> Its a valid point because those are two distinct actions.
>
> > Slightly modify the error message to improve clarity.
> >
> > Signed-off-by: Jane Chu <jane....@oracle.com>
> > ---
> > mm/memory-failure.c | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> > index fc8b517..14de5e2 100644
> > --- a/mm/memory-failure.c
> > +++ b/mm/memory-failure.c
> > @@ -216,10 +216,9 @@ static int kill_proc(struct to_kill *tk, unsigned long
> > pfn, int flags)
> > short addr_lsb = tk->size_shift;
> > int ret;
> >
> > - pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory
> > corruption\n",
> > - pfn, t->comm, t->pid);
> > -
> > if ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm) {
> > + pr_err("Memory failure: %#lx: Killing %s:%d due to hardware
> > memory "
> > + "corruption\n", pfn, t->comm, t->pid);
> > ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr,
> > addr_lsb, current);
> > } else {
> > @@ -229,6 +228,8 @@ static int kill_proc(struct to_kill *tk, unsigned long
> > pfn, int flags)
> > * This could cause a loop when the user sets SIGBUS
> > * to SIG_IGN, but hopefully no one will do that?
> > */
> > + pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to
> > hardware "
> > + "memory corruption\n", pfn, t->comm, t->pid);
> > ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
> > addr_lsb, t); /* synchronous? */
>
> As both the pr_err() messages are very similar, could not we just switch
> between "Killing"
> and "Sending SIGBUS to" based on a variable e.g action_[kill|sigbus]
> evaluated previously
> with ((flags & MF_ACTION_REQUIRED) && t->mm == current->mm).
That might need additional if sentence, which I'm not sure worth doing.
I think that the simplest fix for the reported problem (a confusing message)
is like below:
- pr_err("Memory failure: %#lx: Killing %s:%d due to hardware
memory corruption\n",
+ pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to
hardware memory corruption\n",
pfn, t->comm, t->pid);
Or, if we have a good reason to separate the message for MF_ACTION_REQUIRED and
MF_ACTION_OPTIONAL, that might be OK.
Thanks,
Naoya Horiguchi
