From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id F0336DDDFA for ; Wed, 20 Dec 2006 11:54:18 +1100 (EST) Subject: Re: Bad gcc-4.1.0 leads to Power4 crashes... and power5 too, actually From: Benjamin Herrenschmidt To: Linas Vepstas In-Reply-To: <20061220004653.GL5506@austin.ibm.com> References: <20061220004653.GL5506@austin.ibm.com> Content-Type: text/plain Date: Wed, 20 Dec 2006 11:53:04 +1100 Message-Id: <1166575984.19254.101.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2006-12-19 at 18:46 -0600, Linas Vepstas wrote: > Hi Ben, > > Per xchat, here's the update. I'm guessing I'm using a broken > compiler, as per chain of evidence below ... > > I noticed that linux-2.6.20-rc1-git6 crashes on power4 > in SMP mode: Have you tried a different gcc to confirm ? Ben. > [ 0.000000] [boot]0020 XICS Init > [ 0.000000] i8259 legacy interrupt controller initialized > [ 0.000000] [boot]0021 XICS Done > [ 0.000000] PID hash table entries: 4096 (order: 12, 32768 bytes) > cpu 0x0: Vector: 700 (Program Check) at [c0000000007a3980] > pc: c00000000007d574: .debug_mutex_unlock+0x5c/0x118 > lr: c000000000468068: .__mutex_unlock_slowpath+0x104/0x198 > sp: c0000000007a3c00 > msr: 9000000000029032 > current = 0xc000000000663690 > paca = 0xc000000000663f80 > pid = 0, comm = swapper > enter ? for help > [c0000000007a3c80] c000000000468068 .__mutex_unlock_slowpath+0x104/0x198 > [c0000000007a3d20] c000000000231da8 .double_unlock_mutex+0x3c/0x58 > [c0000000007a3db0] c00000000023b47c .dotest+0x5c/0x370 > [c0000000007a3e50] c00000000023bc0c .locking_selftest+0x47c/0x17fc > [c0000000007a3ef0] c0000000005f06ec .start_kernel+0x1e4/0x344 > [c0000000007a3f90] c0000000000084c8 .start_here_common+0x54/0x8c > 0:mon> > > > However, I also note that the following scrolled by: > init/main.c:81:2: warning: #warning gcc-4.1.0 is known to miscompile the > kernel. A different compiler version is recommended. > > and I have not yet tried a different gcc > > Strangely, linux-2.6.19-git7 crashed with > > [ 0.000000] [boot]0020 XICS Init > [ 0.000000] i8259 legacy interrupt controller initialized > [ 0.000000] [boot]0021 XICS Done > [ 0.000000] PID hash table entries: 4096 (order: 12, 32768 bytes) > System assert at: file: rtas_io_config.c -- line: 195 > rio_hub_num: 10 > drawer_num: 6 > phb_num: 3 > buid: 7 > > which is suspiciously in a similar place. So I am guessing > that it is indeed a compiler problem, the compiler passing > subroutine arguments in some broken way, or something. > > Hmm. seems that linux-2.6.20-rc1-git6 on power5 gives me > > [23178.532001] A-B-B-C-C-A deadlock:failed|failed| ok > |failed|fa|[23178.532028] A-B-C-A-B-C > deadlock:failed|failed| ok |failed|fa|[23178.532054] > A-B-B-C-C-D-D-A deadlock:failed|failed| ok |failed|fa|[23178.532083] > A-B-C-D-B-D-D-A deadlock:failed|failed| ok |failed|fa|[23178.532111] > A-B-C-D-B-C-D-A deadlock:failed|failed| ok |failed|fa|[23178.532139] > double unlock: ok | ok |failed|<0>-------[23178.532171] Kernel BUG > at c00000000007d574 [verbose debug info unavailable] > cpu 0x0: Vector: 700 (Program Check) at [c0000000007a3980] > pc: c00000000007d574: .debug_mutex_unlock+0x5c/0x118 > lr: c000000000468068: .__mutex_unlock_slowpath+0x104/0x198 > sp: c0000000007a3c00 > msr: 8000000000029032 > current = 0xc000000000663690 > paca = 0xc000000000663f80 > pid = 0, comm = swapper > enter ? for help > [c0000000007a3c80] c000000000468068 .__mutex_unlock_slowpath+0x104/0x198 > [c0000000007a3d20] c000000000231da8 .double_unlock_mutex+0x3c/0x58 > [c0000000007a3db0] c00000000023b47c .dotest+0x5c/0x370 > [c0000000007a3e50] c00000000023bc0c .locking_selftest+0x47c/0x17fc > [c0000000007a3ef0] c0000000005f06ec .start_kernel+0x1e4/0x344 > [c0000000007a3f90] c0000000000084c8 .start_here_common+0x54/0x8c > > although linux-2.6.19-git7 worked fine for weeks. > > At any rate, the warning: #warning gcc-4.1.0 should be converted > to a flat-out error. > > --linas > > >