> -----Original Message----- > From: linux-scsi-owner@xxxxxxxxxxxxxxx [mailto:linux-scsi- > owner@xxxxxxxxxxxxxxx] On Behalf Of bugzilla-daemon@xxxxxxxxxxxxxxxxxxx > Sent: Tuesday, 23 September, 2014 4:56 PM > To: linux-scsi@xxxxxxxxxxxxxxx > Subject: [Bug 81861] Oops by mvsas v0.8.16: sas: ataX: end_device-Y:0:Z: dev > error handler -> general protection fault, RIP: mvs_task_prep_ata+0x80/0x3a0 > > https://bugzilla.kernel.org/show_bug.cgi?id=81861 > > --- Comment #16 from linux-ide@xxxxxxxxxxxxx --- > When line-by-line dumping the called constants/vars from: > 469 del_q = TXQ_MODE_I | tag | > 470 (TXQ_CMD_STP << TXQ_CMD_SHIFT) | > 471 (MVS_PHY_ID << TXQ_PHY_SHIFT) | > 472 (mvi_dev->taskfileset << TXQ_SRS_SHIFT); > > using the prepended statements: > printk("slot=%p ", slot); > printk(KERN_INFO "TXQ_MODE_I=%d ", TXQ_MODE_I); > printk(KERN_INFO "tag=%d ", tag); > printk(KERN_INFO "TXQ_CMD_STP=%d ", TXQ_CMD_STP); > printk(KERN_INFO "TXQ_CMD_SHIFT=%d ", TXQ_CMD_SHIFT); > printk(KERN_INFO "MVS_PHY_ID=%d ", MVS_PHY_ID); > printk(KERN_INFO "TXQ_PHY_SHIFT=%d ", TXQ_PHY_SHIFT); > del_q = TXQ_MODE_I | tag | > (TXQ_CMD_STP << TXQ_CMD_SHIFT) | > (MVS_PHY_ID << TXQ_PHY_SHIFT) | > (mvi_dev->taskfileset << TXQ_SRS_SHIFT); > > the kernel crash occurs after printing "TXQ_CMD_SHIFT" or when trying to > output > the value of "MVS_PHY_ID": > [ 529.113152] sas: DONE DISCOVERY on port 0, pid:133, result:0 > [ 529.114313] sas: Enter sas_scsi_recover_host busy: 0 failed: 0 > [ 529.115460] sas: ata7: end_device-6:0:28: dev error handler > [ 529.115522] sas: ata8: end_device-6:0:29: dev error handler > [ 529.118706] sas: ata9: end_device-6:0:30: dev error handler > [ 529.119840] sas: ata10: end_device-6:0:31: dev error handler > [ 529.271634] [mvi=ffff8800d3680000, mvi_dev=ffff8800d36836a0 tag=0 > slot=ffff8800d36a55b8 > [ 529.271753] TXQ_MODE_I=268435456 tag=0 > [ 529.272679] TXQ_CMD_STP=3 TXQ_CMD_SHIFT=29 > [ 529.273618] MVS_PHY_ID=32768 TXQ_PHY_SHIFT=12 tx_prod=44] > [ 529.276091] [mvi=ffff8800d3680000, mvi_dev=ffff8800d3683618 tag=1 > slot=ffff8800d36a5610 > [ 529.276207] TXQ_MODE_I=268435456 tag=1 > [ 529.277095] TXQ_CMD_STP=3 TXQ_CMD_SHIFT=29 > [ 529.278038] MVS_PHY_ID=1 TXQ_PHY_SHIFT=12 tx_prod=46] > [ 529.280271] [mvi=ffff8800d3680000, mvi_dev=ffff8800d3683618 tag=1 > slot=ffff8800d36a5610 > [ 529.280385] TXQ_MODE_I=268435456 tag=1 > [ 529.281445] TXQ_CMD_STP=3 TXQ_CMD_SHIFT=29 > [ 529.282562] MVS_PHY_ID=1 TXQ_PHY_SHIFT=12 tx_prod=48] > [ 529.284894] [mvi=ffff8800d3680000, mvi_dev=ffff8800d36837b0 tag=2 > slot=ffff8800d36a5668 > [ 529.285010] TXQ_MODE_I=268435456 tag=2 > [ 529.286248] TXQ_CMD_STP=3 TXQ_CMD_SHIFT=29 > [ 529.287555] BUG: unable to handle kernel NULL pointer dereference at > 0000000000000257 > [ 529.290225] IP: [<ffffffffa02888bb>] mvs_task_prep+0x7cb/0xe50 [mvsas] > [ 529.291686] PGD 0 > [ 529.293141] Oops: 0000 [#1] SMP > [ 529.294630] Modules linked in: mvsas(OF) libsas scsi_transport_sas > x86_pkg_temp_thermal intel_powerclamp coretemp kvm crct10dif_pclmul > crc32_pclmul ghash_clmulni_intel cryptd serio_raw lpc_ich i915 mei_me mei > drm_kms_helper video netconsole drm configfs mac_hid i2c_algo_bit psmouse > r8169 > ahci mii libahci > > Any suggestions why accessing "MVS_PHY_ID" leads to the kernel NULL pointer > dereference oops? 1. Although MVS_PHY_ID looks like a constant, it's really not: #define MVS_PHY_ID (1U << sas_phy->id) 2. This fault: [ 32.271218] BUG: unable to handle kernel NULL pointer dereference at 0000000000000255 (although 255 looks like a decimal number 0xff, it's really hex 0x255) at this line: 0xffffffffa01c481e <+1838>: mov 0x254(%rbx),%ecx implies that rbx contains 1, so 0x254 + 1 = 0x255. 3. pahole drivers/scsi/mvsas/mv_sas.o shows there are two structures with fields at offset 596: * asd_sas_phy.id * asd_sas_port.sas_addr[8] 4. objdump -drS drivers/scsi/mvsas/mv_sas.o shows only a few lines with 0x254(%something), one of which is the del_q line you've identified: mvs_task_prep_ata(struct mvs_info *mvi, struct mvs_task_exec_info *tei): struct sas_ha_struct *sha = mvi->sas; struct sas_task *task = tei->task; struct domain_device *dev = task->dev; struct sas_phy *sphy = dev->phy; struct asd_sas_phy *sas_phy = sha->sas_phy[sphy->number]; ... del_q = TXQ_MODE_I | tag | (TXQ_CMD_STP << TXQ_CMD_SHIFT) | (MVS_PHY_ID << TXQ_PHY_SHIFT) | (mvi_dev->taskfileset << TXQ_SRS_SHIFT); mvi->tx[mvi->tx_prod] = cpu_to_le32(del_q); MVS_PHY_ID = sas_phy->id = sha->sas_phy[sphy->number] = mvi->sas->sas_phy[dev->phy->number] = mvi->sas->sas_phy[task->dev->phy->number]->id mvi->sas->sas_phy[tei->task->dev->phy->number]->id Looking at the offsets reported by pahole, that means: %rdi->56->344[%rsi->0->0->56->688]->254 mvi->sas->sas_phy is a pointer to a pointer: struct sas_ha_struct { ... struct asd_sas_phy * * sas_phy; /* 344 8 */ You might look for somewhere that could accidentally be setting sas_phy[something] to a for loop index, with a typecast hiding the problem from the compiler. Or, the phy->number value being passed might be out of range; if there were discovery errors, something might not have been initialized like this function expects. --- Rob Elliott HP Server Storage ��.n��������+%������w��{.n�����{������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
