linux-kernel - Re: [syzbot] [kernel?] general protection fault in __cpa_flush

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Message-ID: <20250703010227.2223-1-hdanton@sina.com>
Date: Thu,  3 Jul 2025 09:02:26 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+169412e85b1803dfda81@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [kernel?] general protection fault in __cpa_flush_tlb

> Date: Wed, 02 Jul 2025 07:45:33 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    1343433ed389 Add linux-next specific files for 20250630
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10aa93d4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c1ce97baf6bd6397
> dashboard link: https://syzkaller.appspot.com/bug?extid=169412e85b1803dfda81
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10ed648c580000

#syz test

--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -802,7 +802,6 @@ static void smp_call_function_many_cond(
 
 	/* Check if we need remote execution, i.e., any CPU excluding this one. */
 	if (cpumask_any_and_but(mask, cpu_online_mask, this_cpu) < nr_cpu_ids) {
-		run_remote = true;
 		cfd = this_cpu_ptr(&cfd_data);
 		cpumask_and(cfd->cpumask, mask, cpu_online_mask);
 		__cpumask_clear_cpu(this_cpu, cfd->cpumask);
@@ -816,6 +815,7 @@ static void smp_call_function_many_cond(
 				continue;
 			}
 
+			run_remote = true;
 			csd_lock(csd);
 			if (wait)
 				csd->node.u_flags |= CSD_TYPE_SYNC;
@@ -843,8 +843,6 @@ static void smp_call_function_many_cond(
 			send_call_function_single_ipi(last_cpu);
 		else if (likely(nr_cpus > 1))
 			send_call_function_ipi_mask(cfd->cpumask_ipi);
-		else
-			run_remote = false;
 	}
 
 	/* Check if we need local execution. */
--