September 2025 - Crash-utility - Crash Utility List Archives

Behind the Scenes of Campus Data Centers: Insights from Crash Utility Practices

by yingashley13＠gmail.com

Modern universities rely heavily on digital infrastructure to keep classrooms, online platforms, and administrative systems running smoothly. While students and faculty experience seamless access to online courses, virtual libraries, and academic portals, much of this reliability comes from what happens behind the scenes—specifically within campus data centers. These centers serve as the backbone of digital learning, ensuring continuous access to resources, stable performance, and quick recovery during system failures. In higher education, the importance of uninterrupted online learning cannot be overstated. Many students, for instance, rely on platforms like Myassignmenthelp for academic support, where they might search for options such as take my online class for me (https://myassignmenthelp.com/take-my-online-class.html ). This highlights how critical system reliability is for educational services, whether hosted directly by universities or through third-party academic support platforms. Without dependable infrastructure, both students and institutions risk losing valuable time, resources, and learning opportunities. This is where practices drawn from tools like the Crash Utility come into play. Originally designed for analyzing Linux kernel crash dumps, these tools provide system administrators with detailed insights into why systems fail. For campus data centers, adopting similar diagnostic approaches allows IT teams to quickly identify the root cause of failures, prevent recurring issues, and maintain high system availability. In turn, this ensures that students can log into their learning portals, submit assignments, and access lecture recordings without disruption. Moreover, proactive crash analysis fosters a culture of resilience within educational institutions. Instead of waiting for problems to escalate, IT administrators can anticipate potential bottlenecks or vulnerabilities and resolve them before they affect users. For universities striving to enhance their digital infrastructure, integrating such practices strengthens their ability to support large-scale e-learning initiatives, hybrid classrooms, and research collaborations. In conclusion, while students may only see the front-end of digital learning systems, the true strength of an institution lies in its backend stability. By incorporating insights from crash utility practices, campus data centers can ensure smooth, uninterrupted academic experiences—making education more accessible, reliable, and future-ready.

4 days, 20 hours

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[PATCH v2] vmcoreinfo: read vmcoreinfo using 'vmcoreinfo_data' when unavailable in elf note

by Aditya Gupta

Few vmcores don't have vmcoreinfo elf note, such as those created using virsh-dump. On architectures such as PowerPC64, vmcoreinfo is mandatory to fetch the first_vmalloc_address, for vmcores of upstream linux, since crash-utility commit: commit 5b24e363a898 ("get vmalloc start address from vmcoreinfo") Try reading from the 'vmcoreinfo_data' symbol instead, if the vmcoreinfo crash tries to read in case of diskdump/netdump is empty/missing. The approach to read 'vmcoreinfo_data' was used for a live kernel, which can be reused in the case of missing vmcoreinfo note also, as the 'vmcoreinfo_data' symbol is available with vmcore too Note though, till GDB interface is not initialised, reading from vmcoreinfo_data symbol is not done, so behaviour is same as previously with no vmcoreinfo (only till GDB interface is not initialised) Hence rename 'vmcoreinfo_read_string' in kernel.c to 'vmcoreinfo_read_from_memory', and use it in netdump.c and diskdump.c too. Reported-by: Anushree Mathur <anushree.mathur(a)linux.ibm.com> Tested-by: Anushree Mathur <anushree.mathur(a)linux.ibm.com> Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com> --- Changelog ========= v2: + rename 'is_vmcoreinfo_empty' to netdump/diskdump variants in netdump.c and diskdump.c respectively --- --- defs.h | 1 + diskdump.c | 18 ++++++++++++++++++ kernel.c | 17 ++++++++++++----- netdump.c | 19 +++++++++++++++++++ 4 files changed, 50 insertions(+), 5 deletions(-) diff --git a/defs.h b/defs.h index 156ac0232906..d28484ec44f9 100644 --- a/defs.h +++ b/defs.h @@ -6218,6 +6218,7 @@ void dump_kernel_table(int); void dump_bt_info(struct bt_info *, char *where); void dump_log(int); void parse_kernel_version(char *); +char *vmcoreinfo_read_from_memory(const char *); #define LOG_LEVEL(v) ((v) & 0x07) #define SHOW_LOG_LEVEL (0x1) diff --git a/diskdump.c b/diskdump.c index ce3cbb7b12dd..de907551153d 100644 --- a/diskdump.c +++ b/diskdump.c @@ -1041,6 +1041,13 @@ pfn_to_pos(ulong pfn) return desc_pos; } +/** + * Check if vmcoreinfo in vmcore is missing/empty + */ +static bool is_diskdump_vmcoreinfo_empty(void) +{ + return (dd->sub_header_kdump->size_vmcoreinfo == 0); +} /* * Determine whether a file is a diskdump creation, and if TRUE, @@ -1088,6 +1095,17 @@ is_diskdump(char *file) pc->read_vmcoreinfo = vmcoreinfo_read_string; + /* + * vmcoreinfo can be empty in case of dump collected via virsh-dump + * + * check if vmcoreinfo is not available in vmcore, and try to read + * the vmcoreinfo from memory, using "vmcoreinfo_data" symbol + */ + if (is_diskdump_vmcoreinfo_empty()) { + error(WARNING, "vmcoreinfo is empty, will read from symbols\n"); + pc->read_vmcoreinfo = vmcoreinfo_read_from_memory; + } + if ((pc->flags2 & GET_LOG) && KDUMP_CMPRS_VALID()) { pc->dfd = dd->dfd; pc->readmem = read_diskdump; diff --git a/kernel.c b/kernel.c index e4213d7a663e..0e17874c503c 100644 --- a/kernel.c +++ b/kernel.c @@ -99,7 +99,6 @@ static ulong dump_audit_skb_queue(ulong); static ulong __dump_audit(char *); static void dump_audit(void); static void dump_printk_safe_seq_buf(int); -static char *vmcoreinfo_read_string(const char *); static void check_vmcoreinfo(void); static int is_pvops_xen(void); static int get_linux_banner_from_vmlinux(char *, size_t); @@ -11892,8 +11891,8 @@ dump_printk_safe_seq_buf(int msg_flags) * Returns a string (that has to be freed by the caller) that contains the * value for key or NULL if the key has not been found. */ -static char * -vmcoreinfo_read_string(const char *key) +char * +vmcoreinfo_read_from_memory(const char *key) { char *buf, *value_string, *p1, *p2; size_t value_length; @@ -11903,6 +11902,14 @@ vmcoreinfo_read_string(const char *key) buf = value_string = NULL; + if (!(pc->flags & GDB_INIT)) { + /* + * GDB interface hasn't been initialised yet, so can't + * access vmcoreinfo_data + */ + return NULL; + } + switch (get_symbol_type("vmcoreinfo_data", NULL, NULL)) { case TYPE_CODE_PTR: @@ -11958,10 +11965,10 @@ check_vmcoreinfo(void) switch (get_symbol_type("vmcoreinfo_data", NULL, NULL)) { case TYPE_CODE_PTR: - pc->read_vmcoreinfo = vmcoreinfo_read_string; + pc->read_vmcoreinfo = vmcoreinfo_read_from_memory; break; case TYPE_CODE_ARRAY: - pc->read_vmcoreinfo = vmcoreinfo_read_string; + pc->read_vmcoreinfo = vmcoreinfo_read_from_memory; break; } } diff --git a/netdump.c b/netdump.c index c7ff009e7f90..69100a92e067 100644 --- a/netdump.c +++ b/netdump.c @@ -111,6 +111,14 @@ map_cpus_to_prstatus(void) FREEBUF(nt_ptr); } +/** + * Check if vmcoreinfo in vmcore is missing/empty + */ +static bool is_netdump_vmcoreinfo_empty(void) +{ + return (nd->size_vmcoreinfo == 0); +} + /* * Determine whether a file is a netdump/diskdump/kdump creation, * and if TRUE, initialize the vmcore_data structure. @@ -464,6 +472,17 @@ is_netdump(char *file, ulong source_query) pc->read_vmcoreinfo = vmcoreinfo_read_string; + /* + * vmcoreinfo can be empty in case of dump collected via virsh-dump + * + * check if vmcoreinfo is not available in vmcore, and try to read + * the vmcoreinfo from memory, using "vmcoreinfo_data" symbol + */ + if (is_netdump_vmcoreinfo_empty()) { + error(WARNING, "vmcoreinfo is empty, will read from symbols\n"); + pc->read_vmcoreinfo = vmcoreinfo_read_from_memory; + } + if ((source_query == KDUMP_LOCAL) && (pc->flags2 & GET_OSRELEASE)) kdump_get_osrelease(); -- 2.50.1

1 month, 1 week

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[PATCH v2] Add "log -R" to display human readable Rust symbol name

by Lianbo Jiang

Currently, the log command will display human readable Rust symbol name by default if any, but, sometimes still want to print the original messages from the log buffer(do not demangle). In addition, if the log buffer has lines like "_R ... +" which are not Rust symbols unexpectedly, probably the output will be missed, that is unexpected. To fix above cases, add "log -R" to display human readable Rust symbol name, otherwise still print the original messages. With the patch: crash> log -R ... [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016 [ 2174.308966] Call Trace: [ 2174.311693] <TASK> [ 2174.314033] dump_stack_lvl+0x5d/0x80 [ 2174.318125] panic+0x156/0x32a [ 2174.321539] rust_panic::area_in_hp+0xf7/0x120 [rust_panic] [ 2174.329700] ? console_unlock+0x9c/0x140 [ 2174.334080] ? irq_work_queue+0x2d/0x50 [ 2174.338352] ? __pfx_init_module+0x10/0x10 [rust_panic] [ 2174.344183] <rust_panic::HelloPanic>::step_two+0x20/0xe0 [rust_panic] [ 2174.353698] ? _printk+0x6b/0x90 [ 2174.357303] init_module+0x57/0xff0 [rust_panic] [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic] ... Suggested-by: Kazuhito Hagio <k-hagio-ab(a)nec.com> Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com> --- defs.h | 1 + help.c | 24 +++++++++++++++++++++++- kernel.c | 5 ++++- printk.c | 53 +++++++++++++++++++++++++++++------------------------ 4 files changed, 57 insertions(+), 26 deletions(-) diff --git a/defs.h b/defs.h index 156ac0232906..997145cba9d2 100644 --- a/defs.h +++ b/defs.h @@ -6227,6 +6227,7 @@ void parse_kernel_version(char *); #define SHOW_LOG_CTIME (0x10) #define SHOW_LOG_SAFE (0x20) #define SHOW_LOG_CALLER (0x40) +#define SHOW_LOG_RUST (0x80) void set_cpu(int); void clear_machdep_cache(void); struct stack_hook *gather_text_list(struct bt_info *); diff --git a/help.c b/help.c index 4f071e0bd0a0..78d7a5c70e30 100644 --- a/help.c +++ b/help.c @@ -4026,7 +4026,7 @@ NULL char *help_log[] = { "log", "dump system message buffer", -"[-Ttdmasc]", +"[-TtdmascR]", " This command dumps the kernel log_buf contents in chronological order. The", " command supports the older log_buf formats, which may or may not contain a", " timestamp inserted prior to each message, as well as the newer variable-length", @@ -4053,6 +4053,8 @@ char *help_log[] = { " the CPU id (if in CPU context) that called printk(), if available.", " Generally available on Linux 5.1 to 5.9 kernels configured with", " CONFIG_PRINTK_CALLER or Linux 5.10 and later kernels.", +" -R Display the message text with human readable Rust symbol name if any,", +" otherwise still print the original message text.", " ", "\nEXAMPLES", " Dump the kernel message buffer:\n", @@ -4231,6 +4233,26 @@ char *help_log[] = { " [ 0.014179] [ T29] RAMDISK: [mem 0x3cf4f000-0x437bbfff]", " [ 0.198789] [ C0] DMAR: DRHD: handling fault status reg 3", " ...", +" ", +" Display the message text with human readable Rust symbol name if any,", +" otherwise still print the original message text.\n", +" %s> log -R", +" ...", +" [ 2174.289360] Tainted: [S]=CPU_OUT_OF_SPEC, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE", +" [ 2174.297322] Hardware name: Intel Corporation S2600CWR/S2600CWR, BIOS SE5C610.86B.01.01.0018.072020161249 07/20/2016", +" [ 2174.308966] Call Trace:", +" [ 2174.311693] <TASK>", +" [ 2174.314033] dump_stack_lvl+0x5d/0x80", +" [ 2174.318125] panic+0x156/0x32a", +" [ 2174.321539] rust_panic::area_in_hp+0xf7/0x120 [rust_panic]", +" [ 2174.329700] ? console_unlock+0x9c/0x140", +" [ 2174.334080] ? irq_work_queue+0x2d/0x50", +" [ 2174.338352] ? __pfx_init_module+0x10/0x10 [rust_panic]", +" [ 2174.344183] <rust_panic::HelloPanic>::step_two+0x20/0xe0 [rust_panic]", +" [ 2174.353698] ? _printk+0x6b/0x90", +" [ 2174.357303] init_module+0x57/0xff0 [rust_panic]", +" [ 2174.362456] ? __pfx_init_module+0x10/0x10 [rust_panic]", +" ...", NULL }; diff --git a/kernel.c b/kernel.c index e4213d7a663e..e077275d7ed6 100644 --- a/kernel.c +++ b/kernel.c @@ -5136,7 +5136,7 @@ cmd_log(void) msg_flags = 0; - while ((c = getopt(argcnt, args, "Ttdmasc")) != EOF) { + while ((c = getopt(argcnt, args, "TtdmascR")) != EOF) { switch(c) { case 'T': @@ -5160,6 +5160,9 @@ cmd_log(void) case 'c': msg_flags |= SHOW_LOG_CALLER; break; + case 'R': + msg_flags |= SHOW_LOG_RUST; + break; default: argerrs++; break; diff --git a/printk.c b/printk.c index 51b618e2a434..b8fcc8e58160 100644 --- a/printk.c +++ b/printk.c @@ -202,7 +202,7 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) text = m->text_data + begin; - if (text_len > BUFSIZE) { + if ((msg_flags & SHOW_LOG_RUST) && (text_len > BUFSIZE)) { error(WARNING, "\nThe messages could be truncated!\n"); text_len = BUFSIZE; } @@ -210,36 +210,41 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) for (i = 0, p = text; i < text_len; i++, p++) { if (*p == '\n') fprintf(fp, "\n%s", space(ilen)); - else if (isprint(*p) || isspace(*p)) + else if ((msg_flags & SHOW_LOG_RUST) && (isprint(*p) || isspace(*p))) sprintf(&buf[i], "%c", *p); + else if (isprint(*p) || isspace(*p)) + fputc(*p, fp); else fputc('.', fp); } /* * Try to demangle a mangled Rust symbol(calltrace) from log buffer */ - char *p1 = strstr(buf, "_R"); - if (!p1) - p1 = strstr(buf, "_ZN"); - char *p2 = strrchr(buf, '+'); - if (p1 && p2) { - char mangled[BUFSIZE] = {0}; - char demangled[BUFSIZE] = {0}; - char *res; - size_t slen = p1 - buf; - - if (slen) - memcpy(demangled, buf, slen); - - memcpy(mangled, p1, p2-p1); - res = rust_demangle(mangled, DMGL_RUST); - if (res) { - snprintf(demangled+slen, BUFSIZE-slen, "%s%s", res, p2); - fprintf(fp, "%s",demangled); - free(res); - } - } else - fprintf(fp, "%s", buf); + if (msg_flags & SHOW_LOG_RUST) { + char *p1 = strstr(buf, "_R"); + if (!p1) + p1 = strstr(buf, "_ZN"); + char *p2 = strrchr(buf, '+'); + if (p1 && p2) { + char mangled[BUFSIZE] = {0}; + char demangled[BUFSIZE] = {0}; + char *res; + size_t slen = p1 - buf; + + if (slen) + memcpy(demangled, buf, slen); + + memcpy(mangled, p1, p2-p1); + res = rust_demangle(mangled, DMGL_RUST); + if (res) { + snprintf(demangled+slen, BUFSIZE-slen, "%s%s", res, p2); + fprintf(fp, "%s",demangled); + free(res); + } else + fprintf(fp, "%s", buf); + } else + fprintf(fp, "%s", buf); + } if (msg_flags & SHOW_LOG_DICT) { text = info + OFFSET(printk_info_dev_info) + -- 2.50.1

1 month, 2 weeks

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[PATCH v2 3/3] Enable resolving mangled Rust symbol in lockless ring buffer

by Lianbo Jiang

Without the patch: crash> log ... [ 2174.308966] Call Trace: [ 2174.311693] <TASK> [ 2174.314033] dump_stack_lvl+0x5d/0x80 [ 2174.318125] panic+0x156/0x32a [ 2174.321539] _RNvCscb18lrEyTSA_10rust_panic10area_in_hp+0xf7/0x120 [rust_panic] [ 2174.329700] ? console_unlock+0x9c/0x140 [ 2174.334080] ? irq_work_queue+0x2d/0x50 [ 2174.338352] ? __pfx_init_module+0x10/0x10 [rust_panic] [ 2174.344183] _RNvMCscb18lrEyTSA_10rust_panicNtB2_10HelloPanic8step_two+0x20/0xe0 [rust_panic] [ 2174.353698] ? _printk+0x6b/0x90 ... With the patch: crash> log ... [ 2174.308966] Call Trace: [ 2174.311693] <TASK> [ 2174.314033] dump_stack_lvl+0x5d/0x80 [ 2174.318125] panic+0x156/0x32a [ 2174.321539] rust_panic::area_in_hp+0xf7/0x120 [rust_panic] [ 2174.329700] ? console_unlock+0x9c/0x140 [ 2174.334080] ? irq_work_queue+0x2d/0x50 [ 2174.338352] ? __pfx_init_module+0x10/0x10 [rust_panic] [ 2174.344183] <rust_panic::HelloPanic>::step_two+0x20/0xe0 [rust_panic] [ 2174.353698] ? _printk+0x6b/0x90 ... Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com> --- Note: 1. Add some checks to avoid the risk of buffer overflow. Makefile | 2 +- printk.c | 33 ++++++++++++++++++++++++++++++++- 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index fc1c9588dcfa..b277129f6df2 100644 --- a/Makefile +++ b/Makefile @@ -421,7 +421,7 @@ kernel.o: ${GENERIC_HFILES} kernel.c ${CC} -c ${CRASH_CFLAGS} kernel.c -I${BFD_DIRECTORY} -I${GDB_INCLUDE_DIRECTORY} ${WARNING_OPTIONS} ${WARNING_ERROR} printk.o: ${GENERIC_HFILES} printk.c - ${CC} -c ${CRASH_CFLAGS} printk.c ${WARNING_OPTIONS} ${WARNING_ERROR} + ${CC} -c ${CRASH_CFLAGS} printk.c -I${GDB_INCLUDE_DIRECTORY} ${WARNING_OPTIONS} ${WARNING_ERROR} gdb_interface.o: ${GENERIC_HFILES} gdb_interface.c ${CC} -c ${CRASH_CFLAGS} gdb_interface.c ${WARNING_OPTIONS} ${WARNING_ERROR} diff --git a/printk.c b/printk.c index 95db7e607e4c..ae28c4fa0b21 100644 --- a/printk.c +++ b/printk.c @@ -1,5 +1,6 @@ #include "defs.h" #include <ctype.h> +#include "demangle.h" /* convenience struct for passing many values to helper functions */ struct prb_map { @@ -201,14 +202,44 @@ dump_record(struct prb_map *m, unsigned long id, int msg_flags) text = m->text_data + begin; + if (text_len > BUFSIZE) { + error(WARNING, "\nThe messages could be truncated!\n"); + text_len = BUFSIZE; + } + for (i = 0, p = text; i < text_len; i++, p++) { if (*p == '\n') fprintf(fp, "\n%s", space(ilen)); else if (isprint(*p) || isspace(*p)) - fputc(*p, fp); + sprintf(&buf[i], "%c", *p); else fputc('.', fp); } + /* + * Try to demangle a mangled Rust symbol(calltrace) from log buffer + */ + char *p1 = strstr(buf, "_R"); + if (!p1) + p1 = strstr(buf, "_ZN"); + char *p2 = strchrnul(buf, '+'); + if (p1 && p2) { + char mangled[BUFSIZE] = {0}; + char demangled[BUFSIZE] = {0}; + char *res; + size_t slen = p1 - buf; + + if (slen) + memcpy(demangled, buf, slen); + + memcpy(mangled, p1, p2-p1); + res = rust_demangle(mangled, DMGL_RUST); + if (res) { + snprintf(demangled+slen, BUFSIZE-slen, "%s%s", res, p2); + fprintf(fp, "%s",demangled); + free(res); + } + } else + fprintf(fp, "%s", buf); if (msg_flags & SHOW_LOG_DICT) { text = info + OFFSET(printk_info_dev_info) + -- 2.50.1

1 month, 4 weeks

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[PATCH 2/v2] Fix "mount" MNT_CURSOR (kernels 5.8-6.7)

by Aureau, Georges (Kernel Tools ERT)

[PATCH 2/v2] Fix "mount" MNT_CURSOR (kernels 5.8-6.7): Fix "mount" MNT_CURSOR entries (kernels 5.8-6.7): crash> mount > mount.out WARNING: cannot get super_block from vfsmnt: 0xff35d65eb1cc1820 crash> struct mount.mnt.mnt_sb,mnt.mnt_flags -x 0xff35d65eb1cc1820 mnt.mnt_sb = 0x0, mnt.mnt_flags = 0x10000000, When crashing with running "findmnt" commands, the mount list will have entries with mnt.mnt_flags==MNT_CURSOR (and mnt.mnt_sb==NULL). Such entries should be skipped without errors. Signed-off-by: Georges Aureau <georges.aureau(a)hpe.com> -- defs.h | 2 ++ filesys.c | 15 +++++++++++++++ symbols.c | 4 ++++ 3 files changed, 21 insertions(+) diff --git a/defs.h b/defs.h index 156ac02..3fd7d89 100644 --- a/defs.h +++ b/defs.h @@ -2274,6 +2274,8 @@ struct offset_table { /* stash of commonly-used offsets */ long request_queue_tag_set; long blk_mq_tag_set_flags; long blk_mq_tag_set_shared_tags; + long vfsmount_mnt_flags; + long proc_mounts_cursor; }; struct size_table { /* stash of commonly-used sizes */ diff --git a/filesys.c b/filesys.c index 8d13807..1f8803d 100644 --- a/filesys.c +++ b/filesys.c @@ -1367,6 +1367,10 @@ cmd_mount(void) close_tmpfile(); } +/* For kernels 5.8-6.7, we're skipping show mount cursor entries. + */ +#define MNT_CURSOR 0x10000000 + /* * Do the work for cmd_mount(); */ @@ -1492,6 +1496,15 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context *namespace_contex sbp = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb)); if (!IS_KVADDR(sbp)) { + if (sbp == 0 && VALID_MEMBER(proc_mounts_cursor) && + VALID_MEMBER(vfsmount_mnt_flags)) { + int mnt_flags = INT(vfsmount_buf + OFFSET(vfsmount_mnt_flags)); + if (mnt_flags == MNT_CURSOR) { + if (CRASHDEBUG(1)) + fprintf(stderr,"skipped cursor vfsmnt: 0x%lx\n", *vfsmnt); + continue; + } + } error(WARNING, "cannot get super_block from vfsmnt: 0x%lx\n", *vfsmnt); continue; } @@ -2081,6 +2094,8 @@ vfs_init(void) if (INVALID_MEMBER(vfsmount_mnt_devname)) MEMBER_OFFSET_INIT(mount_mnt_mountpoint, "mount", "mnt_mountpoint"); + MEMBER_OFFSET_INIT(vfsmount_mnt_flags, "vfsmount", "mnt_flags"); + MEMBER_OFFSET_INIT(proc_mounts_cursor, "proc_mounts", "cursor"); MEMBER_OFFSET_INIT(mount_mnt, "mount", "mnt"); MEMBER_OFFSET_INIT(namespace_root, "namespace", "root"); MEMBER_OFFSET_INIT(task_struct_nsproxy, "task_struct", "nsproxy"); diff --git a/symbols.c b/symbols.c index 112bcc6..fd91c2e 100644 --- a/symbols.c +++ b/symbols.c @@ -10691,6 +10691,10 @@ dump_offset_table(char *spec, ulong makestruct) OFFSET(vfsmount_mnt_mountpoint)); fprintf(fp, " vfsmount_mnt_parent: %ld\n", OFFSET(vfsmount_mnt_parent)); + fprintf(fp, " vfsmount_mnt_flags: %ld\n", + OFFSET(vfsmount_mnt_flags)); + fprintf(fp, " proc_mounts_cursor: %ld\n", + OFFSET(proc_mounts_cursor)); fprintf(fp, " mount_mnt_parent: %ld\n", OFFSET(mount_mnt_parent)); fprintf(fp, " mount_mnt_mountpoint: %ld\n",

2 months

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[PATCH 1/v2] Fix "mount <address>"

by Aureau, Georges (Kernel Tools ERT)

[PATCH 1/v2] Fix "mount <address>" The command "mount <address>" is failing on kernels without "super_block.s_files": crash> mount ff35d61d80200000 mount: the super_block.s_files linked list does not exist in this kernel mount: -f option not supported or applicable on this architecture or kernel The MOUNT_PRINT_FILES flags should only be passed when "super_block.s_files" is available. Signed-off-by: Georges Aureau <georges.aureau(a)hpe.com> -- diff --git a/filesys.c b/filesys.c index 8d13807..b4d4f02 100644 --- a/filesys.c +++ b/filesys.c @@ -1296,7 +1296,7 @@ cmd_mount(void) * through it for each search argument entered. */ open_tmpfile(); - show_mounts(0, MOUNT_PRINT_FILES | + show_mounts(0, (VALID_MEMBER(super_block_s_files) ? MOUNT_PRINT_FILES : 0) | (VALID_MEMBER(super_block_s_dirty) ? MOUNT_PRINT_INODES : 0), namespace_context);

2 months

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[PATCH] Fix get_pathname() not handling stacked mounts

by Aureau, Georges (Kernel Tools ERT)

[PATCH] Fix get_pathname() not handling stacked mounts This get_pathname() issue can be duplicated as follow: sudo mkdir -p /tmp/test sudo mount -t tmpfs tmpfs /tmp/test sudo mount --make-private /tmp/test sudo mount --bind /tmp/test /tmp/test sudo mount --bind /tmp/test /tmp/test sudo mount -o remount,ro /tmp/test $ sudo crash /usr/lib/debug/boot/vmlinux-$(uname -r) crash> mount | grep /tmp/test ffff9648e7febc00 ffff9648d91ac800 tmpfs tmpfs /tmp/test ffff9648c9281380 ffff9648d91ac800 tmpfs tmpfs /tmp/test/ ffff9648c8e9a700 ffff9648d91ac800 tmpfs tmpfs / The last mount is not printed properly, and this is impacting diagnostic when looking at vmcore from complex containers mount environments. Signed-off-by: Georges Aureau <georges.aureau(a)hpe.com> -- diff --git a/filesys.c b/filesys.c index 8d13807..af6d616 100644 --- a/filesys.c +++ b/filesys.c @@ -3140,6 +3154,7 @@ get_pathname(ulong dentry, char *pathname, int length, int full, ulong vfsmnt) tmp_vfsmnt = vfsmnt; do { + more_vfsmnt: tmp_dentry = parent; dentry_buf = fill_dentry_cache(tmp_dentry); @@ -3195,6 +3210,7 @@ get_pathname(ulong dentry, char *pathname, int length, int full, ulong vfsmnt) break; else tmp_vfsmnt = mnt_parent; + goto more_vfsmnt; } } else if (VALID_STRUCT(mount)) { if (tmp_vfsmnt) { @@ -3213,6 +3229,7 @@ get_pathname(ulong dentry, char *pathname, int length, int full, ulong vfsmnt) break; else tmp_vfsmnt = mnt_parent + OFFSET(mount_mnt); + goto more_vfsmnt; } } else { @@ -3222,6 +3239,9 @@ get_pathname(ulong dentry, char *pathname, int length, int full, ulong vfsmnt) } } while (tmp_dentry != parent && parent); + if (!STREQ(pathname, "/") && LASTCHAR(pathname) == '/') { + LASTCHAR(pathname) = '\0'; + } if (mnt_buf) FREEBUF(mnt_buf);

2 months

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Patch for Optimize extensions's compilation

by 高建云

Hello, When I tried to build crash extensions for arm64, I found that the default compiler is fixed with gcc. I try to optimize it ,so I send this patch. Looking forward to hearing from you. Best wishes,Thank u

2 months

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[PATCH RFC][makedumpfile 00/10] btf/kallsyms based eppic extension for mm page filtering

by Tao Liu

A) This patchset will introduce the following features to makedumpfile: 1) Enable eppic script for memory pages filtering. 2) Enable btf and kallsyms for symbol type and address resolving. 3) Port maple tree data structures and functions, primarily used for vma iteration. B) The purpose of the features are: 1) Currently makedumpfile filters mm pages based on page flags, because flags can help to determine one page's usage. But this page-flag-checking method lacks of flexibility in certain cases, e.g. if we want to filter those mm pages occupied by GPU during vmcore dumping due to: a) GPU may be taking a large memory and contains sensitive data; b) GPU mm pages have no relations to kernel crash and useless for vmcore analysis. But there is no GPU mm page specific flags, and apparently we don't need to create one just for kdump use. A programmable filtering tool is more suitable for such cases. In addition, different GPU vendors may use different ways for mm pages allocating, programmable filtering is better than hard coding these GPU specific logics into makedumpfile in this case. 2) Currently makedumpfile already contains a programmable filtering tool, aka eppic script, which allows user to write customized code for data erasing. However it has the following drawbacks: a) cannot do mm page filtering. b) need to access to debuginfo of both kernel and modules, which is not applicable in the 2nd kernel. c) Poor performance, making vmcore dumping time unacceptable (See the following performance testing). makedumpfile need to resolve the dwarf data from debuginfo, to get symbols types and addresses. In recent kernel there are dwarf alternatives such as btf/kallsyms which can be used for this purpose. And btf/kallsyms info are already packed within vmcore, so we can use it directly. 3) Maple tree data structures are used in recent kernels, such as vma iteration. So maple tree poring is needed. With these, this patchset introduces an upgraded eppic, which is based on btf/kallsyms symbol resolving, and is programmable for mm page filtering. The following info shows its usage and performance, please note the tests are performed in 1st kernel: $ time ./makedumpfile -d 31 -l /var/crash/127.0.0.1-2025-06-10-18\:03\:12/vmcore /tmp/dwarf.out -x /lib/debug/lib/modules/6.11.8-300.fc41.x86_64/vmlinux --eppic eppic_scripts/filter_amdgpu_mm_pages.c real 14m6.894s user 4m16.900s sys 9m44.695s $ time ./makedumpfile -d 31 -l /var/crash/127.0.0.1-2025-06-10-18\:03\:12/vmcore /tmp/btf.out --eppic eppic_scripts/filter_amdgpu_mm_pages.c real 0m10.672s user 0m9.270s sys 0m1.130s -rw------- 1 root root 367475074 Jun 10 18:06 btf.out -rw------- 1 root root 367475074 Jun 10 21:05 dwarf.out -rw-rw-rw- 1 root root 387181418 Jun 10 18:03 /var/crash/127.0.0.1-2025-06-10-18:03:12/vmcore C) Discussion: 1) GPU types: Currently only tested with amdgpu's mm page filtering, others are not tested. 2) Code structure: There are some similar code shared by makedumpfile and crash, such as maple tree data structure, also I planed to port the btf/kallsyms code to crash as well, so there are code duplications for crash & makedumpfile. Since I havn't working on crash poring, code change on btf/kallsyms is expected. How can we share the code, creating a common library or keep the duplication as it is? 3) OS: The code can work on rhel-10+/rhel9.5+ on x86_64/arm64/s390/ppc64. Others are not tested. D) Testing: 1) If you don't want to create your vmcore, you can find a vmcore which I created with amdgpu mm pages unfiltered [1], the amdgpu mm pages are allocated by program [2]. You can use the vmcore in 1st kernel to filter the amdgpu mm pages by the previous performance testing cmdline. To verify the pages are filtered in crash: Unfiltered: crash> search -c "!QAZXSW@#EDC" ffff96b7fa800000: !QAZXSW@#EDCXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX ffff96b87c800000: !QAZXSW@#EDCXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX crash> rd ffff96b7fa800000 ffff96b7fa800000: 405753585a415121 !QAZXSW@ crash> rd ffff96b87c800000 ffff96b87c800000: 405753585a415121 !QAZXSW@ Filtered: crash> search -c "!QAZXSW@#EDC" crash> rd ffff96b7fa800000 rd: page excluded: kernel virtual address: ffff96b7fa800000 type: "64-bit KVADDR" crash> rd ffff96b87c800000 rd: page excluded: kernel virtual address: ffff96b87c800000 type: "64-bit KVADDR" 2) You can use eppic_scripts/print_all_vma.c against an ordinary vmcore to test only btf/kallsyms functions by output all VMAs if no amdgpu vmcores/machine avaliable. [1]: https://people.redhat.com/~ltao/core/ [2]: https://gist.github.com/liutgnu/a8cbce1c666452f1530e1410d1f352df Tao Liu (10): dwarf_info: Support kernel address randomization dwarf_info: Fix a infinite recursion bug for search_domain Add page filtering function Add btf/kallsyms support for symbol type/address resolving Export necessary btf/kallsyms functions to eppic extension Port the maple tree data structures and functions Supporting main() as the entry of eppic script Enable page filtering for dwarf eppic Enable page filtering for btf/kallsyms eppic Introducing 2 eppic scripts to test the dwarf/btf eppic extension Makefile | 6 +- btf.c | 919 +++++++++++++++++++++++++ btf.h | 176 +++++ dwarf_info.c | 15 +- eppic_maple.c | 431 ++++++++++++ eppic_maple.h | 8 + eppic_scripts/filter_amdgpu_mm_pages.c | 36 + eppic_scripts/print_all_vma.c | 29 + erase_info.c | 123 +++- erase_info.h | 22 + extension_btf.c | 218 ++++++ extension_eppic.c | 41 +- extension_eppic.h | 6 +- kallsyms.c | 371 ++++++++++ kallsyms.h | 42 ++ makedumpfile.c | 21 +- makedumpfile.h | 11 + 17 files changed, 2448 insertions(+), 27 deletions(-) create mode 100644 btf.c create mode 100644 btf.h create mode 100644 eppic_maple.c create mode 100644 eppic_maple.h create mode 100644 eppic_scripts/filter_amdgpu_mm_pages.c create mode 100644 eppic_scripts/print_all_vma.c create mode 100644 extension_btf.c create mode 100644 kallsyms.c create mode 100644 kallsyms.h -- 2.47.0

2 months

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[PATCH] vtop: Translate IEP flag for s390 region and and segment entries.

by Mikhail Zaslonko

Translate and print the IEP (Instruction Execution Protection) flag for Region-Third-Table entries and Segment-Table entries of Format Control 1 for the S390X 'vtop' command like shown below. STE: 0000000033be8ac0 => 0000000015803503 (flags = 03503) flags in binary : AV=0; ACC=0011; F=0; FC=1; P=0; IEP=1; I=0; CS=0; TT=0 Signed-off-by: Mikhail Zaslonko <zaslonko(a)linux.ibm.com> --- s390x.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/s390x.c b/s390x.c index 0e8e2b3..4a462e3 100644 --- a/s390x.c +++ b/s390x.c @@ -65,6 +65,7 @@ #define S390X_RTE_TF 0xc0ULL #define S390X_RTE_TF_10 0x80ULL #define S390X_RTE_TF_01 0x40ULL +#define S390X_RTE_IEP 0x100ULL #define S390X_RTE_P 0x200ULL #define S390X_RTE_FC 0x400ULL #define S390X_RTE_F 0x800ULL @@ -82,6 +83,7 @@ #define S390X_STE_TT_01 0x4ULL #define S390X_STE_CS 0x10ULL #define S390X_STE_I 0x20ULL +#define S390X_STE_IEP 0x100ULL #define S390X_STE_P 0x200ULL #define S390X_STE_FC 0x400ULL #define S390X_STE_F 0x800ULL @@ -979,7 +981,7 @@ static inline int s390x_pte_present(unsigned long x){ /* Print flags of Segment-Table entry with format control = 1 */ static void print_segment_entry_fc1(ulong val) { - fprintf(fp, "AV=%u; ACC=%u%u%u%u; F=%u; FC=%u; P=%u; I=%u; CS=%u; TT=%u%u\n", + fprintf(fp, "AV=%u; ACC=%u%u%u%u; F=%u; FC=%u; P=%u; IEP=%u; I=%u; CS=%u; TT=%u%u\n", !!(val & S390X_STE_AV), !!(val & S390X_STE_ACC_1000), !!(val & S390X_STE_ACC_0100), @@ -988,6 +990,7 @@ static void print_segment_entry_fc1(ulong val) !!(val & S390X_STE_F), !!(val & S390X_STE_FC), !!(val & S390X_STE_P), + !!(val & S390X_STE_IEP), !!(val & S390X_STE_I), !!(val & S390X_STE_CS), !!(val & S390X_STE_TT_10), @@ -1009,7 +1012,7 @@ static void print_segment_entry_fc0(ulong val) /* Print flags of Region-Third-Table entry with format control = 1 */ static void print_region_third_entry_fc1(ulong val) { - fprintf(fp, "AV=%u; ACC=%u%u%u%u; F=%u; FC=%u; P=%u; I=%u; CR=%u; TT=%u%u\n", + fprintf(fp, "AV=%u; ACC=%u%u%u%u; F=%u; FC=%u; P=%u; IEP=%u; I=%u; CR=%u; TT=%u%u\n", !!(val & S390X_RTE_AV), !!(val & S390X_RTE_ACC_1000), !!(val & S390X_RTE_ACC_0100), @@ -1018,6 +1021,7 @@ static void print_region_third_entry_fc1(ulong val) !!(val & S390X_RTE_F), !!(val & S390X_RTE_FC), !!(val & S390X_RTE_P), + !!(val & S390X_RTE_IEP), !!(val & S390X_RTE_I), !!(val & S390X_RTE_CR), !!(val & S390X_RTE_TT_10), -- 2.49.0

2 months

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