[PATCH] s390/kexec: Consolidate crash_map/unmap_reserved_pages() and arch_kexec_protect(unprotect)_crashkres()
From: Xunlei Pang
Date: Wed Mar 30 2016 - 07:47:51 EST
Commit 3f625002581b ("kexec: introduce a protection mechanism
for the crashkernel reserved memory") is a similar mechanism
for protecting the crash kernel reserved memory to previous
crash_map/unmap_reserved_pages() implementation, the new one
is more generic in name and cleaner in code (besides, some
arch may not be allowed to unmap the pgtable).
Therefore, this patch consolidates them, and uses the new
arch_kexec_protect(unprotect)_crashkres() to replace former
crash_map/unmap_reserved_pages() which by now has been only
used by S390.
The consolidation work needs the crash memory to be mapped
initially, so get rid of S390 crash kernel memblock removal
in reserve_crashkernel(). Once kdump kernel is loaded, the
new arch_kexec_protect_crashkres() implemented for S390 will
actually unmap the pgtable like before.
The patch also fixed a S390 crash_shrink_memory() bad page warning
in passing due to not using memblock_reserve():
BUG: Bad page state in process bash pfn:7e400
page:000003d101f90000 count:0 mapcount:1 mapping: (null) index:0x0
flags: 0x0()
page dumped because: nonzero mapcount
Modules linked in: ghash_s390 prng aes_s390 des_s390 des_generic
CPU: 0 PID: 1558 Comm: bash Not tainted 4.6.0-rc1-next-20160327 #1
0000000073007a58 0000000073007ae8 0000000000000002 0000000000000000
0000000073007b88 0000000073007b00 0000000073007b00 000000000022cf4e
0000000000a579b8 00000000007b0dd6 0000000000791a8c
000000000000000b
0000000073007b48 0000000073007ae8 0000000000000000 0000000000000000
070003d100000001 0000000000112f20 0000000073007ae8 0000000073007b48
Call Trace:
([<0000000000112e0c>] show_trace+0x5c/0x78)
([<0000000000112ed4>] show_stack+0x6c/0xe8)
([<00000000003f28dc>] dump_stack+0x84/0xb8)
([<0000000000235454>] bad_page+0xec/0x158)
([<00000000002357a4>] free_pages_prepare+0x2e4/0x308)
([<00000000002383a2>] free_hot_cold_page+0x42/0x198)
([<00000000001c45e0>] crash_free_reserved_phys_range+0x60/0x88)
([<00000000001c49b0>] crash_shrink_memory+0xb8/0x1a0)
([<000000000015bcae>] kexec_crash_size_store+0x46/0x60)
([<000000000033d326>] kernfs_fop_write+0x136/0x180)
([<00000000002b253c>] __vfs_write+0x3c/0x100)
([<00000000002b35ce>] vfs_write+0x8e/0x190)
([<00000000002b4ca0>] SyS_write+0x60/0xd0)
([<000000000063067c>] system_call+0x244/0x264)
Cc: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Xunlei Pang <xlpang@xxxxxxxxxx>
---
Tested kexec/kdump on S390x
arch/s390/kernel/machine_kexec.c | 86 ++++++++++++++++++++++------------------
arch/s390/kernel/setup.c | 7 ++--
include/linux/kexec.h | 2 -
kernel/kexec.c | 12 ------
kernel/kexec_core.c | 11 +----
5 files changed, 54 insertions(+), 64 deletions(-)
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 2f1b721..1ec6cfc 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -35,6 +35,52 @@ extern const unsigned long long relocate_kernel_len;
#ifdef CONFIG_CRASH_DUMP
/*
+ * Map or unmap crashkernel memory
+ */
+static void crash_map_pages(int enable)
+{
+ unsigned long size = resource_size(&crashk_res);
+
+ BUG_ON(crashk_res.start % KEXEC_CRASH_MEM_ALIGN ||
+ size % KEXEC_CRASH_MEM_ALIGN);
+ if (enable)
+ vmem_add_mapping(crashk_res.start, size);
+ else {
+ vmem_remove_mapping(crashk_res.start, size);
+ if (size)
+ os_info_crashkernel_add(crashk_res.start, size);
+ else
+ os_info_crashkernel_add(0, 0);
+ }
+}
+
+/*
+ * Map crashkernel memory
+ */
+static void crash_map_reserved_pages(void)
+{
+ crash_map_pages(1);
+}
+
+/*
+ * Unmap crashkernel memory
+ */
+static void crash_unmap_reserved_pages(void)
+{
+ crash_map_pages(0);
+}
+
+void arch_kexec_protect_crashkres(void)
+{
+ crash_unmap_reserved_pages();
+}
+
+void arch_kexec_unprotect_crashkres(void)
+{
+ crash_map_reserved_pages();
+}
+
+/*
* PM notifier callback for kdump
*/
static int machine_kdump_pm_cb(struct notifier_block *nb, unsigned long action,
@@ -43,12 +89,12 @@ static int machine_kdump_pm_cb(struct notifier_block *nb, unsigned long action,
switch (action) {
case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
- if (crashk_res.start)
+ if (kexec_crash_image)
crash_map_reserved_pages();
break;
case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
- if (crashk_res.start)
+ if (kexec_crash_image)
crash_unmap_reserved_pages();
break;
default:
@@ -147,42 +193,6 @@ static int kdump_csum_valid(struct kimage *image)
}
/*
- * Map or unmap crashkernel memory
- */
-static void crash_map_pages(int enable)
-{
- unsigned long size = resource_size(&crashk_res);
-
- BUG_ON(crashk_res.start % KEXEC_CRASH_MEM_ALIGN ||
- size % KEXEC_CRASH_MEM_ALIGN);
- if (enable)
- vmem_add_mapping(crashk_res.start, size);
- else {
- vmem_remove_mapping(crashk_res.start, size);
- if (size)
- os_info_crashkernel_add(crashk_res.start, size);
- else
- os_info_crashkernel_add(0, 0);
- }
-}
-
-/*
- * Map crashkernel memory
- */
-void crash_map_reserved_pages(void)
-{
- crash_map_pages(1);
-}
-
-/*
- * Unmap crashkernel memory
- */
-void crash_unmap_reserved_pages(void)
-{
- crash_map_pages(0);
-}
-
-/*
* Give back memory to hypervisor before new kdump is loaded
*/
static int machine_kexec_prepare_kdump(void)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index d3f9688..5f00437 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -603,7 +603,7 @@ static void __init reserve_crashkernel(void)
crashk_res.start = crash_base;
crashk_res.end = crash_base + crash_size - 1;
insert_resource(&iomem_resource, &crashk_res);
- memblock_remove(crash_base, crash_size);
+ memblock_reserve(crash_base, crash_size);
pr_info("Reserving %lluMB of memory at %lluMB "
"for crashkernel (System RAM: %luMB)\n",
crash_size >> 20, crash_base >> 20,
@@ -871,7 +871,6 @@ void __init setup_arch(char **cmdline_p)
setup_memory();
check_initrd();
- reserve_crashkernel();
#ifdef CONFIG_CRASH_DUMP
/*
* Be aware that smp_save_dump_cpus() triggers a system reset.
@@ -890,7 +889,9 @@ void __init setup_arch(char **cmdline_p)
/*
* Create kernel page tables and switch to virtual addressing.
*/
- paging_init();
+ paging_init();
+
+ reserve_crashkernel();
/* Setup default console */
conmode_default();
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index f82d6a2..c76641c 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -230,8 +230,6 @@ extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *);
void crash_save_cpu(struct pt_regs *regs, int cpu);
void crash_save_vmcoreinfo(void);
-void crash_map_reserved_pages(void);
-void crash_unmap_reserved_pages(void);
void arch_crash_save_vmcoreinfo(void);
__printf(1, 2)
void vmcoreinfo_append_str(const char *fmt, ...);
diff --git a/kernel/kexec.c b/kernel/kexec.c
index b73dc21..4384672 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -136,9 +136,6 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
if (ret)
return ret;
- if (flags & KEXEC_ON_CRASH)
- crash_map_reserved_pages();
-
if (flags & KEXEC_PRESERVE_CONTEXT)
image->preserve_context = 1;
@@ -161,12 +158,6 @@ out:
if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
arch_kexec_protect_crashkres();
- /*
- * Once the reserved memory is mapped, we should unmap this memory
- * before returning
- */
- if (flags & KEXEC_ON_CRASH)
- crash_unmap_reserved_pages();
kimage_free(image);
return ret;
}
@@ -232,9 +223,6 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
result = do_kexec_load(entry, nr_segments, segments, flags);
- if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
- arch_kexec_protect_crashkres();
-
mutex_unlock(&kexec_mutex);
return result;
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index f826e11..58cd872 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -953,7 +953,6 @@ int crash_shrink_memory(unsigned long new_size)
start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
- crash_map_reserved_pages();
crash_free_reserved_phys_range(end, crashk_res.end);
if ((start == end) && (crashk_res.parent != NULL))
@@ -967,7 +966,6 @@ int crash_shrink_memory(unsigned long new_size)
crashk_res.end = end - 1;
insert_resource(&iomem_resource, ram_res);
- crash_unmap_reserved_pages();
unlock:
mutex_unlock(&kexec_mutex);
@@ -1549,17 +1547,12 @@ int kernel_kexec(void)
}
/*
- * Add and remove page tables for crashkernel memory
+ * Protection mechanism for crashkernel reserved memory after
+ * the kdump kernel is loaded.
*
* Provide an empty default implementation here -- architecture
* code may override this
*/
-void __weak crash_map_reserved_pages(void)
-{}
-
-void __weak crash_unmap_reserved_pages(void)
-{}
-
void __weak arch_kexec_protect_crashkres(void)
{}
--
1.8.3.1