mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread (03151c6e) · Commits · 戴 / test

Action Required memory error should happen only when a processor is about to access to a corrupted memory, so it's synchronous and only affects current process/thread. Recently commit ("mm, memory_failure: don't send BUS_MCEERR_AO for action required error") fixed the issue that Action Required memory could unnecessarily send SIGBUS to the processes which share the error memory. But we still have another issue that we could send SIGBUS to a wrong thread. This is because collect_procs() and task_early_kill() fails to add the current process to "to-kill" list. So this patch is suggesting to fix it. With this fix, SIGBUS(BUS_MCEERR_AR) is never sent to non-current process/thread. Signed-off-by:

Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Acked-by:

Tony Luck <tony.luck@intel.com> Acked-by:

Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/1591321039-22141-3-git-send-email-naoya.horiguchi@nec.com Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c

+16 −7

Original line number	Diff line number	Diff line
		@@ -212,15 +212,13 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
		short addr_lsb = tk->size_shift;
		int ret = 0;

		if ((t->mm == current->mm) \|\| !(flags & MF_ACTION_REQUIRED))
		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
		pfn, t->comm, t->pid);

		if (flags & MF_ACTION_REQUIRED) {
		if (t->mm == current->mm)
		WARN_ON_ONCE(t != current);
		ret = force_sig_mceerr(BUS_MCEERR_AR,
		(void __user *)tk->addr, addr_lsb);
		/* send no signal to non-current processes */
		} else {
		/*
		* Don't use force here, it's convenient if the signal
		@@ -419,14 +417,25 @@ static struct task_struct find_early_kill_thread(struct task_struct tsk)
		* to be signaled when some page under the process is hwpoisoned.
		* Return task_struct of the dedicated thread (main thread unless explicitly
		* specified) if the process is "early kill," and otherwise returns NULL.
		*
		* Note that the above is true for Action Optional case, but not for Action
		* Required case where SIGBUS should sent only to the current thread.
		*/
		static struct task_struct task_early_kill(struct task_struct tsk,
		int force_early)
		{
		if (!tsk->mm)
		return NULL;
		if (force_early)
		return tsk;
		if (force_early) {
		/*
		* Comparing ->mm here because current task might represent
		* a subthread, while tsk always points to the main thread.
		*/
		if (tsk->mm == current->mm)
		return current;
		else
		return NULL;
		}
		return find_early_kill_thread(tsk);
		}

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