* Handling spin table in kdump
@ 2012-05-22 12:42 Suzuki K. Poulose
2012-05-22 15:34 ` McClintock Matthew-B29882
0 siblings, 1 reply; 5+ messages in thread
From: Suzuki K. Poulose @ 2012-05-22 12:42 UTC (permalink / raw)
To: kexec, linuxppc-dev; +Cc: Matthew McClintock, Sebastian Andrzej Siewior
Hi
I came across the following issue while testing Kdump on an SMP
board(Currituck) running a non-SMP kernel. Even though the kernel is UP,
the device-tree has the nodes for second CPU and the related details.
The kexec tool adds the spin table area as a reserved section in the
device tree for the dump capture kernel. This value is read from the
'cpu-release-addr'.
But now, if the spin table is not located within the 'Reserved region'
for the crash kernel, the dump capture kernel would fail to boot,
hitting a BUG in mm/bootmem.c as in [1].
This is because we try to reserve a region which is not available to the
kernel.
So I am wondering how is this handled really on an SMP board (Fsl_bookE).
There are two possible solutions :
1) Do not reserve the regions for the spin-table, as we will use
only the crashing CPU in the second kernel(maxcpus=1).
2) Add the spin-table region to the available memory regions passed
to the kernel by kexec-tools.
I have tested (1) and it works fine for me. Yet to test (2).
Thoughts ?
Thanks
Suzuki
[1] Kernel Bug
----------------
Linux version 3.3.0-rc5 (root@suzukikp.in.ibm.com) (gcc version 4.3.4
[gcc-4_3-branch revision 152973] (GCC) ) #12 Tue May 22 18:03:01 IST2
Found legacy serial port 0 for /plb/opb/serial@10000000
mem=20010000000, taddr=20010000000, irq=0, clk=1851851, speed=115200
------------[ cut here ]------------
kernel BUG at mm/bootmem.c:351!
Vector: 700 (Program Check) at [c8a61e90]
pc: c847f91c: mark_bootmem+0xa0/0x14c
lr: c8472670: do_init_bootmem+0x1ac/0x218
sp: c8a61f40
msr: 21000
current = 0xc8a4a500
pid = 0, comm = swapper
kernel BUG at mm/bootmem.c:351!
enter ? for help
[c8a61f70] c8472670 do_init_bootmem+0x1ac/0x218
[c8a61f90] c847025c setup_arch+0x1bc/0x234
[c8a61fb0] c846b62c start_kernel+0x98/0x358
[c8a61ff0] c80000b4 _start+0xb4/0xf8
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: Handling spin table in kdump 2012-05-22 12:42 Handling spin table in kdump Suzuki K. Poulose @ 2012-05-22 15:34 ` McClintock Matthew-B29882 2012-05-24 6:09 ` [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel Suzuki K. Poulose 0 siblings, 1 reply; 5+ messages in thread From: McClintock Matthew-B29882 @ 2012-05-22 15:34 UTC (permalink / raw) To: Suzuki K. Poulose Cc: linuxppc-dev@lists.ozlabs.org, Sebastian Andrzej Siewior, kexec@lists.infradead.org On Tue, May 22, 2012 at 7:42 AM, Suzuki K. Poulose <suzuki@in.ibm.com> wrot= e: > Hi > > I came across the following issue while testing Kdump on an SMP > board(Currituck) running a non-SMP kernel. Even though the kernel is UP, > the device-tree has the nodes for second CPU and the related details. > > > The kexec tool adds the spin table area as a reserved section in the devi= ce > tree for the dump capture kernel. This value is read from the > 'cpu-release-addr'. > > But now, if the spin table is not located within the 'Reserved region' fo= r > the crash kernel, the dump capture kernel would fail to boot, hitting a B= UG > in mm/bootmem.c as in [1]. > > This is because we try to reserve a region which is not available to the > kernel. > > So I am wondering how is this handled really on an SMP board (Fsl_bookE). > > There are two possible solutions : > 1) Do not reserve the regions for the spin-table, as we will use > only the crashing CPU in the second kernel(maxcpus=3D1). > > > 2) Add the spin-table region to the available memory regions passed > to the kernel by kexec-tools. > > I have tested (1) and it works fine for me. Yet to test (2). > > > Thoughts ? I would think option 1 is acceptable. The crash kernel will never attempt to use the memory outside of the crash kernel region therefore it does not need to be reserved. However, I thought we were able to boot SMP into the crash kernel on our parts... not sure how that effects things (although the maxcpus=3D1 here is a perfectly acceptable and safer thing to do anyways) -M > > > Thanks > Suzuki > > > > [1] Kernel Bug > ---------------- > > > Linux version 3.3.0-rc5 (root@suzukikp.in.ibm.com) (gcc version 4.3.4 > [gcc-4_3-branch revision 152973] (GCC) ) #12 Tue May 22 18:03:01 IST2 > Found legacy serial port 0 for /plb/opb/serial@10000000 > =A0mem=3D20010000000, taddr=3D20010000000, irq=3D0, clk=3D1851851, speed= =3D115200 > ------------[ cut here ]------------ > kernel BUG at mm/bootmem.c:351! > Vector: 700 (Program Check) at [c8a61e90] > =A0 =A0pc: c847f91c: mark_bootmem+0xa0/0x14c > =A0 =A0lr: c8472670: do_init_bootmem+0x1ac/0x218 > =A0 =A0sp: c8a61f40 > =A0 msr: 21000 > =A0current =3D 0xc8a4a500 > =A0 =A0pid =A0 =3D 0, comm =3D swapper > kernel BUG at mm/bootmem.c:351! > enter ? for help > [c8a61f70] c8472670 do_init_bootmem+0x1ac/0x218 > [c8a61f90] c847025c setup_arch+0x1bc/0x234 > [c8a61fb0] c846b62c start_kernel+0x98/0x358 > [c8a61ff0] c80000b4 _start+0xb4/0xf8 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev= ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel 2012-05-22 15:34 ` McClintock Matthew-B29882 @ 2012-05-24 6:09 ` Suzuki K. Poulose 2012-06-18 6:27 ` Suzuki K. Poulose 2012-07-13 6:33 ` Simon Horman 0 siblings, 2 replies; 5+ messages in thread From: Suzuki K. Poulose @ 2012-05-24 6:09 UTC (permalink / raw) To: kexec; +Cc: B29882, Simon Horman, linuxppc-dev As of now, the kexec reserves the spin-table for all the CPUs on an SMP machine. The spin-table is pointed to by the cpu-release-addr property in the device-tree. Reserving the spin-table in the crash kernel will cause a BUG(), if the table lies outside the memory reserved for the crashkernel. Disable reserving the spin-table regions and use maxcpus=1 to use only the crashing CPU to boot the crash kernel. Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com> --- kexec/arch/ppc/crashdump-powerpc.c | 19 +++++++++++++------ kexec/arch/ppc/fixup_dtb.c | 4 ++++ 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/kexec/arch/ppc/crashdump-powerpc.c b/kexec/arch/ppc/crashdump-powerpc.c index 1bef69b..4c8c75d 100644 --- a/kexec/arch/ppc/crashdump-powerpc.c +++ b/kexec/arch/ppc/crashdump-powerpc.c @@ -262,10 +262,19 @@ static void ulltoa(unsigned long long i, char *str) } } +/* Append str to cmdline */ +static void add_cmdline(char *cmdline, char *str) +{ + int cmdlen = strlen(cmdline) + strlen(str); + if (cmdlen > (COMMAND_LINE_SIZE - 1)) + die("Command line overflow\n"); + strcat(cmdline, str); +} + static int add_cmdline_param(char *cmdline, unsigned long long addr, char *cmdstr, char *byte) { - int cmdlen, len, align = 1024; + int align = 1024; char str[COMMAND_LINE_SIZE], *ptr; /* Passing in =xxxK / =xxxM format. Saves space required in cmdline.*/ @@ -284,11 +293,8 @@ static int add_cmdline_param(char *cmdline, unsigned long long addr, ptr += strlen(str); ulltoa(addr, ptr); strcat(str, byte); - len = strlen(str); - cmdlen = strlen(cmdline) + len; - if (cmdlen > (COMMAND_LINE_SIZE - 1)) - die("Command line overflow\n"); - strcat(cmdline, str); + + add_cmdline(cmdline, str); dbgprintf("Command line after adding elfcorehdr: %s\n", cmdline); @@ -365,6 +371,7 @@ int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline, */ add_cmdline_param(mod_cmdline, elfcorehdr, " elfcorehdr=", "K"); add_cmdline_param(mod_cmdline, saved_max_mem, " savemaxmem=", "M"); + add_cmdline(mod_cmdline, " maxcpus=1"); return 0; } diff --git a/kexec/arch/ppc/fixup_dtb.c b/kexec/arch/ppc/fixup_dtb.c index e9890a4..f832026 100644 --- a/kexec/arch/ppc/fixup_dtb.c +++ b/kexec/arch/ppc/fixup_dtb.c @@ -172,6 +172,9 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf) } } +#if 0 + /* XXX: Do not reserve spin-table for CPUs. */ + /* Add reserve regions for cpu-release-addr */ nodeoffset = fdt_node_offset_by_prop_value(blob_buf, -1, "device_type", "cpu", 4); while (nodeoffset != -FDT_ERR_NOTFOUND) { @@ -201,6 +204,7 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf) nodeoffset = fdt_node_offset_by_prop_value(blob_buf, nodeoffset, "device_type", "cpu", 4); } +#endif out: print_fdt_reserve_regions(blob_buf); ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel 2012-05-24 6:09 ` [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel Suzuki K. Poulose @ 2012-06-18 6:27 ` Suzuki K. Poulose 2012-07-13 6:33 ` Simon Horman 1 sibling, 0 replies; 5+ messages in thread From: Suzuki K. Poulose @ 2012-06-18 6:27 UTC (permalink / raw) To: Simon Horman; +Cc: B29882, linuxppc-dev, kexec On 05/24/2012 11:39 AM, Suzuki K. Poulose wrote: > As of now, the kexec reserves the spin-table for all the CPUs > on an SMP machine. The spin-table is pointed to by the > cpu-release-addr property in the device-tree. Reserving the > spin-table in the crash kernel will cause a BUG(), if the table > lies outside the memory reserved for the crashkernel. > > Disable reserving the spin-table regions and use maxcpus=1 to > use only the crashing CPU to boot the crash kernel. > > Signed-off-by: Suzuki K. Poulose<suzuki@in.ibm.com> Simon, Any response on this one ? I have tested this on a Currituck board (476, SMP) with a UP kernel. Without this patch, the secondary kernel hits 'PANIC' in boot while trying to reserve a memory(the spin table), outside the memory range(crash reserve). Thanks Suzuki > --- > > kexec/arch/ppc/crashdump-powerpc.c | 19 +++++++++++++------ > kexec/arch/ppc/fixup_dtb.c | 4 ++++ > 2 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/kexec/arch/ppc/crashdump-powerpc.c b/kexec/arch/ppc/crashdump-powerpc.c > index 1bef69b..4c8c75d 100644 > --- a/kexec/arch/ppc/crashdump-powerpc.c > +++ b/kexec/arch/ppc/crashdump-powerpc.c > @@ -262,10 +262,19 @@ static void ulltoa(unsigned long long i, char *str) > } > } > > +/* Append str to cmdline */ > +static void add_cmdline(char *cmdline, char *str) > +{ > + int cmdlen = strlen(cmdline) + strlen(str); > + if (cmdlen> (COMMAND_LINE_SIZE - 1)) > + die("Command line overflow\n"); > + strcat(cmdline, str); > +} > + > static int add_cmdline_param(char *cmdline, unsigned long long addr, > char *cmdstr, char *byte) > { > - int cmdlen, len, align = 1024; > + int align = 1024; > char str[COMMAND_LINE_SIZE], *ptr; > > /* Passing in =xxxK / =xxxM format. Saves space required in cmdline.*/ > @@ -284,11 +293,8 @@ static int add_cmdline_param(char *cmdline, unsigned long long addr, > ptr += strlen(str); > ulltoa(addr, ptr); > strcat(str, byte); > - len = strlen(str); > - cmdlen = strlen(cmdline) + len; > - if (cmdlen> (COMMAND_LINE_SIZE - 1)) > - die("Command line overflow\n"); > - strcat(cmdline, str); > + > + add_cmdline(cmdline, str); > > dbgprintf("Command line after adding elfcorehdr: %s\n", cmdline); > > @@ -365,6 +371,7 @@ int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline, > */ > add_cmdline_param(mod_cmdline, elfcorehdr, " elfcorehdr=", "K"); > add_cmdline_param(mod_cmdline, saved_max_mem, " savemaxmem=", "M"); > + add_cmdline(mod_cmdline, " maxcpus=1"); > return 0; > } > > diff --git a/kexec/arch/ppc/fixup_dtb.c b/kexec/arch/ppc/fixup_dtb.c > index e9890a4..f832026 100644 > --- a/kexec/arch/ppc/fixup_dtb.c > +++ b/kexec/arch/ppc/fixup_dtb.c > @@ -172,6 +172,9 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf) > } > } > > +#if 0 > + /* XXX: Do not reserve spin-table for CPUs. */ > + > /* Add reserve regions for cpu-release-addr */ > nodeoffset = fdt_node_offset_by_prop_value(blob_buf, -1, "device_type", "cpu", 4); > while (nodeoffset != -FDT_ERR_NOTFOUND) { > @@ -201,6 +204,7 @@ static void fixup_reserve_regions(struct kexec_info *info, char *blob_buf) > nodeoffset = fdt_node_offset_by_prop_value(blob_buf, nodeoffset, > "device_type", "cpu", 4); > } > +#endif > > out: > print_fdt_reserve_regions(blob_buf); > > > _______________________________________________ > kexec mailing list > kexec@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/kexec > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel 2012-05-24 6:09 ` [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel Suzuki K. Poulose 2012-06-18 6:27 ` Suzuki K. Poulose @ 2012-07-13 6:33 ` Simon Horman 1 sibling, 0 replies; 5+ messages in thread From: Simon Horman @ 2012-07-13 6:33 UTC (permalink / raw) To: Suzuki K. Poulose; +Cc: B29882, linuxppc-dev, kexec On Thu, May 24, 2012 at 11:39:45AM +0530, Suzuki K. Poulose wrote: > As of now, the kexec reserves the spin-table for all the CPUs > on an SMP machine. The spin-table is pointed to by the > cpu-release-addr property in the device-tree. Reserving the > spin-table in the crash kernel will cause a BUG(), if the table > lies outside the memory reserved for the crashkernel. > > Disable reserving the spin-table regions and use maxcpus=1 to > use only the crashing CPU to boot the crash kernel. > > Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com> Thanks, applied. Sorry for not seeing this (much) earlier. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-07-13 6:53 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-05-22 12:42 Handling spin table in kdump Suzuki K. Poulose 2012-05-22 15:34 ` McClintock Matthew-B29882 2012-05-24 6:09 ` [PATCH] [ppc] Do not reserve cpu spin-table for crash kernel Suzuki K. Poulose 2012-06-18 6:27 ` Suzuki K. Poulose 2012-07-13 6:33 ` Simon Horman
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