From: Mahesh Salgaonkar Date: Mon, 23 Apr 2018 04:59:27 +0000 (+0530) Subject: powerpc/mce: Fix a bug where mce loops on memory UE. X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=75ecfb49516c53da00c57b9efe48fa3f5504a791;p=openwrt%2Fstaging%2Fblogic.git 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: 01eaac2b0591 ("powerpc/mce: Hookup ierror (instruction) UE errors") Fixes: ba41e1e1ccb9 ("powerpc/mce: Hookup derror (load/store) UE errors") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Mahesh Salgaonkar Signed-off-by: Balbir Singh Reviewed-by: Balbir Singh Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c index fe6fc63251fe..38c5b4764bfe 100644 --- a/arch/powerpc/kernel/mce_power.c +++ b/arch/powerpc/kernel/mce_power.c @@ -441,7 +441,6 @@ static int mce_handle_ierror(struct pt_regs *regs, if (pfn != ULONG_MAX) { *phys_addr = (pfn << PAGE_SHIFT); - handled = 1; } } } @@ -532,9 +531,7 @@ static int mce_handle_derror(struct pt_regs *regs, * kernel/exception-64s.h */ if (get_paca()->in_mce < MAX_MCE_DEPTH) - if (!mce_find_instr_ea_and_pfn(regs, addr, - phys_addr)) - handled = 1; + mce_find_instr_ea_and_pfn(regs, addr, phys_addr); } found = 1; } @@ -572,7 +569,7 @@ static long mce_handle_error(struct pt_regs *regs, const struct mce_ierror_table itable[]) { struct mce_error_info mce_err = { 0 }; - uint64_t addr, phys_addr; + uint64_t addr, phys_addr = ULONG_MAX; uint64_t srr1 = regs->msr; long handled;