makedumpfile: Add --non-mmap option to disable mmap() manually
This is a backport of the following upstream commit:
commit a895dc8
Author: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Date: Thu Dec 12 16:40:12 2013 +0900
[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@mxc.nes.nec.co.jp>
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@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
WANG Chao
parent
778ab7d0c4
commit
89a4cb24e0
@ -0,0 +1,161 @@
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From a895dc8f2a17f7dac9d3d63de1cea4720557625d Mon Sep 17 00:00:00 2001
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From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
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Date: Thu, 12 Dec 2013 16:40:12 +0900
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Subject: [PATCH 1/2] [PATCH] Add --non-mmap option to disable mmap() manually.
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When --non-mmap option is specified, makedumpfile doesn't use
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mmap() even if /proc/vmcore supports mmap().
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Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
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---
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makedumpfile.8 | 11 +++++++++++
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makedumpfile.c | 29 +++++++++++++++++++----------
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makedumpfile.h | 9 +++++++++
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print_info.c | 6 ++++++
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4 files changed, 45 insertions(+), 10 deletions(-)
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diff --git a/makedumpfile-1.5.4/makedumpfile.8 b/makedumpfile-1.5.4/makedumpfile.8
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index f50a011..227b6f7 100644
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--- a/makedumpfile-1.5.4/makedumpfile.8
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+++ b/makedumpfile-1.5.4/makedumpfile.8
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@@ -395,6 +395,17 @@ If you feel the cyclic mode is too slow, please try this mode.
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# makedumpfile \-\-non\-cyclic \-d 31 \-x vmlinux /proc/vmcore dumpfile
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.TP
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+\fB\-\-non\-mmap\fR
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+Never use \fBmmap(2)\fR to read \fIVMCORE\fR even if it supports \fBmmap(2)\fR.
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+Generally, reading \fIVMCORE\fR with \fBmmap(2)\fR is faster than without it,
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+so ordinary users don't need to specify this option.
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+This option is mainly for debugging.
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+.br
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+.B Example:
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+.br
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+# makedumpfile \-\-non\-mmap \-d 31 \-x vmlinux /proc/vmcore dumpfile
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+
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+.TP
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\fB\-\-xen-syms\fR \fIXEN-SYMS\fR
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Specify the \fIXEN-SYMS\fR with debug information to analyze the xen's memory usage.
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This option extracts the part of xen and domain-0.
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diff --git a/makedumpfile-1.5.4/makedumpfile.c b/makedumpfile-1.5.4/makedumpfile.c
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index 600fb5d..b3af28b 100644
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--- a/makedumpfile-1.5.4/makedumpfile.c
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+++ b/makedumpfile-1.5.4/makedumpfile.c
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@@ -272,7 +272,7 @@ update_mmap_range(off_t offset, int initial) {
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static int
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is_mapped_with_mmap(off_t offset) {
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- if (info->flag_usemmap
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+ if (info->flag_usemmap == MMAP_ENABLE
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&& offset >= info->mmap_start_offset
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&& offset < info->mmap_end_offset)
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return TRUE;
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@@ -320,7 +320,7 @@ read_from_vmcore(off_t offset, void *bufptr, unsigned long size)
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{
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const off_t failed = (off_t)-1;
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- if (info->flag_usemmap) {
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+ if (info->flag_usemmap == MMAP_ENABLE) {
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if (!read_with_mmap(offset, bufptr, size)) {
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ERRMSG("Can't read the dump memory(%s) with mmap().\n",
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info->name_memory);
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@@ -3175,14 +3175,14 @@ out:
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if (info->dump_level & DL_EXCLUDE_FREE)
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setup_page_is_buddy();
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- if (!initialize_mmap()) {
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- /* this kernel does not support mmap of vmcore */
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- DEBUG_MSG("Kernel can't mmap vmcore, using reads.\n");
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- info->flag_usemmap = FALSE;
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+ if (info->flag_usemmap == MMAP_TRY && initialize_mmap()) {
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+ DEBUG_MSG("mmap() is available on the kernel.\n");
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+ info->flag_usemmap = MMAP_ENABLE;
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} else {
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- DEBUG_MSG("read %s with mmap()\n", info->name_memory);
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- info->flag_usemmap = TRUE;
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- }
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+ DEBUG_MSG("The kernel doesn't support mmap(),");
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+ DEBUG_MSG("read() will be used instead.\n");
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+ info->flag_usemmap = MMAP_DISABLE;
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+ }
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return TRUE;
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}
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@@ -8947,6 +8947,7 @@ static struct option longopts[] = {
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{"non-cyclic", no_argument, NULL, OPT_NON_CYCLIC},
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{"cyclic-buffer", required_argument, NULL, OPT_CYCLIC_BUFFER},
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{"eppic", required_argument, NULL, OPT_EPPIC},
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+ {"non-mmap", no_argument, NULL, OPT_NON_MMAP},
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{0, 0, 0, 0}
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};
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@@ -8972,7 +8973,12 @@ main(int argc, char *argv[])
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* By default, makedumpfile works in constant memory space.
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*/
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info->flag_cyclic = TRUE;
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-
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+
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+ /*
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+ * By default, makedumpfile try to use mmap(2) to read /proc/vmcore.
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+ */
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+ info->flag_usemmap = MMAP_TRY;
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+
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info->block_order = DEFAULT_ORDER;
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message_level = DEFAULT_MSG_LEVEL;
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while ((opt = getopt_long(argc, argv, "b:cDd:EFfg:hi:lpRvXx:", longopts,
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@@ -9069,6 +9075,9 @@ main(int argc, char *argv[])
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case OPT_NON_CYCLIC:
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info->flag_cyclic = FALSE;
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break;
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+ case OPT_NON_MMAP:
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+ info->flag_usemmap = MMAP_DISABLE;
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+ break;
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case OPT_XEN_VMCOREINFO:
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info->flag_read_vmcoreinfo = 1;
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info->name_vmcoreinfo = optarg;
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diff --git a/makedumpfile-1.5.4/makedumpfile.h b/makedumpfile-1.5.4/makedumpfile.h
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index 517e16e..fe88eff 100644
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--- a/makedumpfile-1.5.4/makedumpfile.h
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+++ b/makedumpfile-1.5.4/makedumpfile.h
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@@ -128,6 +128,14 @@ enum {
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MADDR_XEN
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};
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+/*
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+ * State of mmap(2)
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+ */
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+enum {
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+ MMAP_DISABLE,
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+ MMAP_TRY,
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+ MMAP_ENABLE,
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+};
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static inline int
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test_bit(int nr, unsigned long addr)
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@@ -1741,6 +1749,7 @@ struct elf_prstatus {
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#define OPT_NON_CYCLIC OPT_START+10
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#define OPT_CYCLIC_BUFFER OPT_START+11
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#define OPT_EPPIC OPT_START+12
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+#define OPT_NON_MMAP OPT_START+13
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/*
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* Function Prototype.
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diff --git a/makedumpfile-1.5.4/print_info.c b/makedumpfile-1.5.4/print_info.c
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index d7a8600..90b6cee 100644
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--- a/makedumpfile-1.5.4/print_info.c
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+++ b/makedumpfile-1.5.4/print_info.c
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@@ -196,6 +196,12 @@ print_usage(void)
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MSG(" same as v1.4.4 or before.\n");
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MSG(" If you feel the cyclic mode is too slow, please try this mode.\n");
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MSG("\n");
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+ MSG(" [--non-mmap]:\n");
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+ MSG(" Never use mmap(2) to read VMCORE even if it supports mmap(2).\n");
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+ MSG(" Generally, reading VMCORE with mmap(2) is faster than without it,\n");
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+ MSG(" so ordinary users don't need to specify this option.\n");
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+ MSG(" This option is mainly for debugging.\n");
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+ MSG("\n");
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MSG(" [--xen-syms XEN-SYMS]:\n");
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MSG(" Specify the XEN-SYMS to analyze Xen's memory usage.\n");
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MSG("\n");
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--
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1.8.4.2
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@ -92,6 +92,7 @@ Patch610: kexec-tools-2.0.4-makedumpfile-cache-Reuse-entry-in-pending-list.patch
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Patch612: kexec-tools-2.0.4-makedumpfile-Understand-v3.11-rc4-dmesg.patch
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Patch613: kexec-tools-2.0.4-makedumpfile-Assign-non-printable-value-as-short-option.patch
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Patch614: kexec-tools-2.0.4-makedumpfile-Add-help-and-man-message-for-help.patch
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Patch615: kexec-tools-2.0.4-makedumpfile-Add-non-mmap-option-to-disable-mmap-manually.patch
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%description
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kexec-tools provides /sbin/kexec binary that facilitates a new
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@ -137,6 +138,7 @@ tar -z -x -v -f %{SOURCE19}
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%patch302 -p1
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%patch613 -p1
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%patch614 -p1
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%patch615 -p1
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tar -z -x -v -f %{SOURCE13}
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