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Subject[PATCH 3/5] HWPOISON: Handle hwpoison in current process
Date
From:	"Luck, Tony" <tony.luck@intel.com>

From: Andi Kleen <andi@firstfloor.org>

When hardware poison handles the current process use
a forced signal with _AR severity.

[Tony: changed some function names .. the "_ao" suffix was no longer meaningful]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
mm/memory-failure.c | 39 ++++++++++++++++++++++-----------------
1 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 2b43ba0..6ccb8a6 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -186,33 +186,38 @@ int hwpoison_filter(struct page *p)
EXPORT_SYMBOL_GPL(hwpoison_filter);

/*
- * Send all the processes who have the page mapped an ``action optional''
- * signal.
+ * Send one process who has the page mapped a SIGBUS. It might
+ * be able to catch it and initiate its own task level recovery.
*/
-static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
+static int user_recovery(struct task_struct *t, unsigned long addr, int trapno,
unsigned long pfn, struct page *page)
{
struct siginfo si;
int ret;

printk(KERN_ERR
- "MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
- pfn, t->comm, t->pid);
+ "MCE %#lx: Killing %s:%d due to hardware memory corruption\n",
+ pfn, t->comm, t->pid);
si.si_signo = SIGBUS;
si.si_errno = 0;
- si.si_code = BUS_MCEERR_AO;
si.si_addr = (void *)addr;
#ifdef __ARCH_SI_TRAPNO
si.si_trapno = trapno;
#endif
si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
- /*
- * Don't use force here, it's convenient if the signal
- * can be temporarily blocked.
- * This could cause a loop when the user sets SIGBUS
- * to SIG_IGN, but hopefully no one will do that?
- */
- ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
+ if (t == current) {
+ si.si_code = BUS_MCEERR_AR;
+ ret = force_sig_info(SIGBUS, &si, t);
+ } else {
+ /*
+ * Don't use force here, it's convenient if the signal
+ * can be temporarily blocked.
+ * This could cause a loop when the user sets SIGBUS
+ * to SIG_IGN, but hopefully noone will do that?
+ */
+ si.si_code = BUS_MCEERR_AO;
+ ret = send_sig_info(SIGBUS, &si, t);
+ }
if (ret < 0)
printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
t->comm, t->pid, ret);
@@ -330,14 +335,14 @@ static void add_to_kill(struct task_struct *tsk, struct page *p,
}

/*
- * Kill the processes that have been collected earlier.
+ * Signal the processes that have been collected earlier.
*
* Only do anything when DOIT is set, otherwise just free the list
* (this is used for clean pages which do not need killing)
* Also when FAIL is set do a force kill because something went
* wrong earlier.
*/
-static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
+static void kill_procs(struct list_head *to_kill, int doit, int trapno,
int fail, struct page *page, unsigned long pfn)
{
struct to_kill *tk, *next;
@@ -362,7 +367,7 @@ static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
* check for that, but we need to tell the
* process anyways.
*/
- else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
+ else if (user_recovery(tk->tsk, tk->addr, trapno,
pfn, page) < 0)
printk(KERN_ERR
"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
@@ -961,7 +966,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
* use a more force-full uncatchable kill to prevent
* any accesses to the poisoned memory.
*/
- kill_procs_ao(&tokill, !!PageDirty(ppage), trapno,
+ kill_procs(&tokill, !!PageDirty(ppage), trapno,
ret != SWAP_SUCCESS, p, pfn);

return ret;
--
1.7.3.1


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