From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40W4Z96BQQzF24b for ; Wed, 25 Apr 2018 12:55:29 +1000 (AEST) In-Reply-To: <152445952887.3244.567606806755236868.stgit@jupiter.in.ibm.com> To: Mahesh J Salgaonkar , linuxppc-dev From: Michael Ellerman Subject: Re: powerpc/mce: Fix a bug where mce loops on memory UE. Message-Id: <40W4Z938p6z9s0t@ozlabs.org> Date: Wed, 25 Apr 2018 12:55:29 +1000 (AEST) List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2018-04-23 at 04:59:27 UTC, Mahesh J Salgaonkar wrote: > From: Mahesh Salgaonkar > > 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: > [ 1476.541984] Severe Machine check interrupt [Recovered] > [ 1476.541985] NIP: [000000001002588c] PID: 7109 Comm: find > [ 1476.541986] Initiator: CPU > [ 1476.541987] Error type: UE [Load/Store] > [ 1476.541988] Effective address: 00007fffd2755940 > [ 1476.541989] Physical address: 000020181a080000 > [...] > [ 1476.542003] Severe Machine check interrupt [Recovered] > [ 1476.542004] NIP: [000000001002588c] PID: 7109 Comm: find > [ 1476.542005] Initiator: CPU > [ 1476.542006] Error type: UE [Load/Store] > [ 1476.542006] Effective address: 00007fffd2755940 > [ 1476.542007] Physical address: 000020181a080000 > [ 1476.542010] Severe Machine check interrupt [Recovered] > [ 1476.542012] NIP: [000000001002588c] PID: 7109 Comm: find > [ 1476.542013] Initiator: CPU > [ 1476.542014] Error type: UE [Load/Store] > [ 1476.542015] Effective address: 00007fffd2755940 > [ 1476.542016] Physical address: 000020181a080000 > [ 1476.542448] Memory failure: 0x20181a08: recovery action for dirty LRU page: Recovered > [ 1476.542452] Memory failure: 0x20181a08: already hardware poisoned > [ 1476.542453] Memory failure: 0x20181a08: already hardware poisoned > [ 1476.542454] Memory failure: 0x20181a08: already hardware poisoned > [ 1476.542455] Memory failure: 0x20181a08: already hardware poisoned > [ 1476.542456] Memory failure: 0x20181a08: already hardware poisoned > [ 1476.542457] Memory failure: 0x20181a08: already hardware poisoned > [...] > [ 1490.972174] Watchdog CPU:38 Hard LOCKUP > > After this patch we see: > > [ 325.384336] Severe Machine check interrupt [Not recovered] > [ 325.384338] NIP: [00007fffaae585f4] PID: 7168 Comm: find > [ 325.384339] Initiator: CPU > [ 325.384341] Error type: UE [Load/Store] > [ 325.384343] Effective address: 00007fffaafe28ac > [ 325.384345] Physical address: 00002017c0bd0000 > [ 325.384350] find[7168]: unhandled signal 7 at 00007fffaae585f4 nip 00007fffaae585f4 lr 00007fffaae585e0 code 4 > [ 325.388574] 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") > Signed-off-by: Mahesh Salgaonkar > Signed-off-by: Balbir Singh > Reviewed-by: Balbir Singh Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/75ecfb49516c53da00c57b9efe48fa cheers