This patch fixes a bug where a kernel warning is triggered when performing
a memory hotplug on ppc64. This warning may also occur on any architecture
that has multiple sections per memory block.
[ 78.300767] ------------[ cut here ]------------
[ 78.300768] WARNING: at ../drivers/base/memory.c:210
[ 78.300769] Modules linked in: rpadlpar_io(X) rpaphp(X) tcp_diag udp_diag
inet_diag unix_diag af_packet_diag netlink_diag af_packet xfs libcrc32c
ibmveth(X) rtc_generic btrfs xor raid6_pq xts gf128mul dm_crypt sd_mod sr_mod
cdrom crc_t10dif ibmvscsi(X) scsi_transport_srp scsi_tgt dm_mod sg scsi_mod
autofs4
[ 78.300789] Supported: Yes, External
[ 78.300791] CPU: 1 PID: 3090 Comm: systemd-udevd Tainted: G X
3.12.45-1-default #1
[ 78.300793] task: c0000004d7d1d970 ti: c0000004d7b90000 task.ti:
c0000004d7b90000
[ 78.300794] NIP: c0000000004fcff8 LR: c0000000004fda84 CTR: 0000000000000000
[ 78.300795] REGS: c0000004d7b93930 TRAP: 0700 Tainted: G X
(3.12.45-1-default)
[ 78.300796] MSR: 8000000000029033 <SF,EE,ME,IR,DR,RI,LE> CR: 24088848 XER:
00000000
[ 78.300800] CFAR: c0000000004fcf98 SOFTE: 1
GPR00: 0000000000000537 c0000004d7b93bb0 c000000000e7f200 0000000000053000
GPR04: 0000000000001000 0000000000000001 c000000000e0f200 0000000000000000
GPR08: 0000000000000000 0000000000000001 0000000000000537 00000000014dc000
GPR12: 0000000000054000 c00000000e7f0900 0000000010041040 0000000000000000
GPR16: 00000100206f0010 000000001003ff78 000000001006c824 00000000100410b0
GPR20: 000000001003ff90 000000001006c00c 000001002073cd20 00000100206f0760
GPR24: 00000100206f85a0 c00000000076d950 c0000004ef7c95e0 c0000004d7b93e00
GPR28: c0000004de601738 0000000000000001 c000000001218f80 00000000003fffff
[ 78.300818] NIP [c0000000004fcff8] memory_block_action+0x258/0x2e0
[ 78.300820] LR [c0000000004fda84] memory_subsys_online+0x54/0x100
[ 78.300821] Call Trace:
[ 78.300822] [c0000004d7b93bb0] [c000000009071ce0] 0xc000000009071ce0
(unreliable)
[ 78.300824] [c0000004d7b93c40] [c0000000004fda84]
memory_subsys_online+0x54/0x100
[ 78.300826] [c0000004d7b93c70] [c0000000004df784] device_online+0xb4/0x120
[ 78.300828] [c0000004d7b93cb0] [c0000000004fd738] store_mem_state+0x88/0x220
[ 78.300830] [c0000004d7b93cf0] [c0000000004db448] dev_attr_store+0x68/0xa0
[ 78.300833] [c0000004d7b93d30] [c00000000031f938] sysfs_write_file+0xf8/0x1d0
[ 78.300835] [c0000004d7b93d90] [c00000000027d29c] vfs_write+0xec/0x250
[ 78.300837] [c0000004d7b93de0] [c00000000027dfdc] SyS_write+0x6c/0xf0
[ 78.300839] [c0000004d7b93e30] [c00000000000a17c] syscall_exit+0x0/0x7c
[ 78.300840] Instruction dump:
[ 78.300841] 780a0560 79482ea4 7ce94214 2fa70000 41de0014 7d09402a 396b4000
7907ffe3
[ 78.300844] 4082ff54 3cc2fff9 8926b83a 69290001 <0b090000> 2fa90000 40de006c
3860fff0
[ 78.300847] ---[ end trace dfec8da06ebbc762 ]---
The warning is triggered because there is a udev rule that automatically
tries to online memory after it has been added. The udev rule varies from
distro to distro, but will generally look something like:
SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"
On any architecture that uses memory_probe_store to reserve memory,
this can interrupt the memory reservation process. This patch modifies
memory_probe_store to take the hotplug sysfs lock to prevent the online
of added memory before the completion of the probe.
Signed-off-by: John Allen <jal...@linux.vnet.ibm.com>
---
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 2804aed..baf7a22 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -457,6 +457,10 @@ memory_probe_store(struct device *dev, struct
device_attribute *attr,
if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
return -EINVAL;
+ ret = lock_device_hotplug_sysfs();
+ if (ret)
+ return ret;
+
for (i = 0; i < sections_per_block; i++) {
nid = memory_add_physaddr_to_nid(phys_addr);
ret = add_memory(nid, phys_addr,
@@ -467,6 +471,8 @@ memory_probe_store(struct device *dev, struct
device_attribute *attr,
phys_addr += MIN_MEMORY_BLOCK_SIZE;
}
+ unlock_device_hotplug();
+
ret = count;
out:
return ret;
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