[PATCH 4/5] makedumpfile: Add --non-mmap option to disable mmap() manually
WANG Chao
chaowang at redhat.com
Tue Jan 7 09:00:13 UTC 2014
This is a backport of the following upstream commit:
commit 414d3ed
Author: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp>
Date: Thu Dec 12 16:40:12 2013 +0900
Add --non-mmap option to disable mmap() manually.
When --non-mmap option is specified, makedumpfile doesn't use
mmap() even if /proc/vmcore supports mmap().
Having this patch, user can switch between mmap() and read() when
accessing vmcore. Whenever user feels necessary to use readmem on vmcore
(buggy code in mmap path, debug purpose, etc.), --non-mmap can do this
favor.
Signed-off-by: WANG Chao <chaowang at redhat.com>
---
...-non-mmap-option-to-disable-mmap-manually.patch | 161 +++++++++++++++++++++
kexec-tools.spec | 2 +
2 files changed, 163 insertions(+)
create mode 100644 kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch
diff --git a/kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch b/kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch
new file mode 100644
index 0000000..8a9ee47
--- /dev/null
+++ b/kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch
@@ -0,0 +1,161 @@
+From a895dc8f2a17f7dac9d3d63de1cea4720557625d Mon Sep 17 00:00:00 2001
+From: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp>
+Date: Thu, 12 Dec 2013 16:40:12 +0900
+Subject: [PATCH 1/2] [PATCH] Add --non-mmap option to disable mmap() manually.
+
+When --non-mmap option is specified, makedumpfile doesn't use
+mmap() even if /proc/vmcore supports mmap().
+
+Signed-off-by: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp>
+---
+ makedumpfile.8 | 11 +++++++++++
+ makedumpfile.c | 29 +++++++++++++++++++----------
+ makedumpfile.h | 9 +++++++++
+ print_info.c | 6 ++++++
+ 4 files changed, 45 insertions(+), 10 deletions(-)
+
+diff --git a/makedumpfile-1.5.4/makedumpfile.8 b/makedumpfile-1.5.4/makedumpfile.8
+index f50a011..227b6f7 100644
+--- a/makedumpfile-1.5.4/makedumpfile.8
++++ b/makedumpfile-1.5.4/makedumpfile.8
+@@ -395,6 +395,17 @@ If you feel the cyclic mode is too slow, please try this mode.
+ # makedumpfile \-\-non\-cyclic \-d 31 \-x vmlinux /proc/vmcore dumpfile
+
+ .TP
++\fB\-\-non\-mmap\fR
++Never use \fBmmap(2)\fR to read \fIVMCORE\fR even if it supports \fBmmap(2)\fR.
++Generally, reading \fIVMCORE\fR with \fBmmap(2)\fR is faster than without it,
++so ordinary users don't need to specify this option.
++This option is mainly for debugging.
++.br
++.B Example:
++.br
++# makedumpfile \-\-non\-mmap \-d 31 \-x vmlinux /proc/vmcore dumpfile
++
++.TP
+ \fB\-\-xen-syms\fR \fIXEN-SYMS\fR
+ Specify the \fIXEN-SYMS\fR with debug information to analyze the xen's memory usage.
+ This option extracts the part of xen and domain-0.
+diff --git a/makedumpfile-1.5.4/makedumpfile.c b/makedumpfile-1.5.4/makedumpfile.c
+index 600fb5d..b3af28b 100644
+--- a/makedumpfile-1.5.4/makedumpfile.c
++++ b/makedumpfile-1.5.4/makedumpfile.c
+@@ -272,7 +272,7 @@ update_mmap_range(off_t offset, int initial) {
+ static int
+ is_mapped_with_mmap(off_t offset) {
+
+- if (info->flag_usemmap
++ if (info->flag_usemmap == MMAP_ENABLE
+ && offset >= info->mmap_start_offset
+ && offset < info->mmap_end_offset)
+ return TRUE;
+@@ -320,7 +320,7 @@ read_from_vmcore(off_t offset, void *bufptr, unsigned long size)
+ {
+ const off_t failed = (off_t)-1;
+
+- if (info->flag_usemmap) {
++ if (info->flag_usemmap == MMAP_ENABLE) {
+ if (!read_with_mmap(offset, bufptr, size)) {
+ ERRMSG("Can't read the dump memory(%s) with mmap().\n",
+ info->name_memory);
+@@ -3175,14 +3175,14 @@ out:
+ if (info->dump_level & DL_EXCLUDE_FREE)
+ setup_page_is_buddy();
+
+- if (!initialize_mmap()) {
+- /* this kernel does not support mmap of vmcore */
+- DEBUG_MSG("Kernel can't mmap vmcore, using reads.\n");
+- info->flag_usemmap = FALSE;
++ if (info->flag_usemmap == MMAP_TRY && initialize_mmap()) {
++ DEBUG_MSG("mmap() is available on the kernel.\n");
++ info->flag_usemmap = MMAP_ENABLE;
+ } else {
+- DEBUG_MSG("read %s with mmap()\n", info->name_memory);
+- info->flag_usemmap = TRUE;
+- }
++ DEBUG_MSG("The kernel doesn't support mmap(),");
++ DEBUG_MSG("read() will be used instead.\n");
++ info->flag_usemmap = MMAP_DISABLE;
++ }
+
+ return TRUE;
+ }
+@@ -8947,6 +8947,7 @@ static struct option longopts[] = {
+ {"non-cyclic", no_argument, NULL, OPT_NON_CYCLIC},
+ {"cyclic-buffer", required_argument, NULL, OPT_CYCLIC_BUFFER},
+ {"eppic", required_argument, NULL, OPT_EPPIC},
++ {"non-mmap", no_argument, NULL, OPT_NON_MMAP},
+ {0, 0, 0, 0}
+ };
+
+@@ -8972,7 +8973,12 @@ main(int argc, char *argv[])
+ * By default, makedumpfile works in constant memory space.
+ */
+ info->flag_cyclic = TRUE;
+-
++
++ /*
++ * By default, makedumpfile try to use mmap(2) to read /proc/vmcore.
++ */
++ info->flag_usemmap = MMAP_TRY;
++
+ info->block_order = DEFAULT_ORDER;
+ message_level = DEFAULT_MSG_LEVEL;
+ while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lpRvXx:", longopts,
+@@ -9069,6 +9075,9 @@ main(int argc, char *argv[])
+ case OPT_NON_CYCLIC:
+ info->flag_cyclic = FALSE;
+ break;
++ case OPT_NON_MMAP:
++ info->flag_usemmap = MMAP_DISABLE;
++ break;
+ case OPT_XEN_VMCOREINFO:
+ info->flag_read_vmcoreinfo = 1;
+ info->name_vmcoreinfo = optarg;
+diff --git a/makedumpfile-1.5.4/makedumpfile.h b/makedumpfile-1.5.4/makedumpfile.h
+index 517e16e..fe88eff 100644
+--- a/makedumpfile-1.5.4/makedumpfile.h
++++ b/makedumpfile-1.5.4/makedumpfile.h
+@@ -128,6 +128,14 @@ enum {
+ MADDR_XEN
+ };
+
++/*
++ * State of mmap(2)
++ */
++enum {
++ MMAP_DISABLE,
++ MMAP_TRY,
++ MMAP_ENABLE,
++};
+
+ static inline int
+ test_bit(int nr, unsigned long addr)
+@@ -1741,6 +1749,7 @@ struct elf_prstatus {
+ #define OPT_NON_CYCLIC OPT_START+10
+ #define OPT_CYCLIC_BUFFER OPT_START+11
+ #define OPT_EPPIC OPT_START+12
++#define OPT_NON_MMAP OPT_START+13
+
+ /*
+ * Function Prototype.
+diff --git a/makedumpfile-1.5.4/print_info.c b/makedumpfile-1.5.4/print_info.c
+index d7a8600..90b6cee 100644
+--- a/makedumpfile-1.5.4/print_info.c
++++ b/makedumpfile-1.5.4/print_info.c
+@@ -196,6 +196,12 @@ print_usage(void)
+ MSG(" same as v1.4.4 or before.\n");
+ MSG(" If you feel the cyclic mode is too slow, please try this mode.\n");
+ MSG("\n");
++ MSG(" [--non-mmap]:\n");
++ MSG(" Never use mmap(2) to read VMCORE even if it supports mmap(2).\n");
++ MSG(" Generally, reading VMCORE with mmap(2) is faster than without it,\n");
++ MSG(" so ordinary users don't need to specify this option.\n");
++ MSG(" This option is mainly for debugging.\n");
++ MSG("\n");
+ MSG(" [--xen-syms XEN-SYMS]:\n");
+ MSG(" Specify the XEN-SYMS to analyze Xen's memory usage.\n");
+ MSG("\n");
+--
+1.8.4.2
+
diff --git a/kexec-tools.spec b/kexec-tools.spec
index 1edd4ed..c83cc64 100644
--- a/kexec-tools.spec
+++ b/kexec-tools.spec
@@ -92,6 +92,7 @@ Patch610: kexec-tools-2.0.4-makedumpfile-cache-Reuse-entry-in-pending-list.patch
Patch612: kexec-tools-2.0.4-makedumpfile-Understand-v3.11-rc4-dmesg.patch
Patch613: kexec-tools-2.0.4-makedumpfile-Assign-non-printable-value-as-short-option.patch
Patch614: kexec-tools-2.0.4-makedumpfile-Add-help-and-man-message-for-help.patch
+Patch615: kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch
%description
kexec-tools provides /sbin/kexec binary that facilitates a new
@@ -137,6 +138,7 @@ tar -z -x -v -f %{SOURCE19}
%patch302 -p1
%patch613 -p1
%patch614 -p1
+%patch615 -p1
tar -z -x -v -f %{SOURCE13}
--
1.8.4.2
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