NAME
vm - virtual memory
SYNOPSIS
vm [-p | -P vma | -M mm | -v | -m | -x | -d | [-R reference] [pid | task]]
[-f vm_flags]
DESCRIPTION
This command displays basic virtual memory information of a context,
consisting of a pointer to its mm_struct and page directory, its RSS and
total virtual memory size; and a list of pointers to each vm_area_struct,
its starting and ending address, vm_flags value, and file pathname. If no
arguments are entered, the current context is used. Additionally, the -p
option translates each virtual page of each VM area to its physical address.
The -R option, typically invoked from "foreach vm", searches for references
to a supplied number, address, or filename argument, and prints only the
essential information leading up to and including the reference.
Alternatively, the -m or -v options may be used to dump the task's mm_struct
or all of its vm_area_structs respectively. The -p, -v, -m, -R and -f
options are all mutually exclusive.
-p translate each virtual page to its physical address, or if
the page is not mapped, its swap device and offset, or
filename and offset.
-P vma similar to -p, but only translate the pages belonging to the
specified VM area of a context.
-M mm if the mm_struct address has been removed from the task_struct
of an exiting task, the virtual memory data cannot be displayed.
However, if the address can be determined from the kernel stack,
it can be entered manually in order to try to resurrect the
virtual memory data of the task.
NOTE: this option is only used when the task's mm_struct is NULL.
-R reference search for references to this number or filename.
-m dump the mm_struct associated with the task.
-v dump all of the vm_area_structs associated with the task.
-x override the default output format for the -m or -v options
with hexadecimal format.
-d override the default output format for the -m or -v options
with decimal format.
-f vm_flags translate the bits of a FLAGS (vm_flags) value.
pid a process PID.
task a hexadecimal task_struct pointer.
EXAMPLES
Display the virtual memory data of the current context:
crash> vm
PID: 30986 TASK: c0440000 CPU: 0 COMMAND: "bash"
MM PGD RSS TOTAL_VM
c303fe20 c4789000 88k 1728k
VMA START END FLAGS FILE
c0d1f540 8048000 80ad000 1875 /bin/bash
c0d1f400 80ad000 80b3000 1873 /bin/bash
c0d1f880 80b3000 80ec000 77
c0d1f0c0 40000000 40012000 875 /lib/ld-2.1.1.so
c0d1f700 40012000 40013000 873 /lib/ld-2.1.1.so
c0d1fe00 40013000 40014000 77
c0d1f580 40014000 40016000 73
c0d1f280 4001a000 4004b000 75 /usr/lib/libncurses.so.4.2
c0d1f100 4004b000 40054000 73 /usr/lib/libncurses.so.4.2
c0d1f600 40054000 40057000 73
c0d1f9c0 40057000 40059000 75 /lib/libdl-2.1.1.so
c0d1f800 40059000 4005a000 73 /lib/libdl-2.1.1.so
c0d1fd00 4005a000 40140000 75 /lib/libc-2.1.1.so
c0d1fe40 40140000 40145000 73 /lib/libc-2.1.1.so
c0d1f780 40145000 40148000 73
c0d1f140 40148000 40150000 75 /lib/libnss_files-2.1.1.so
c0d1fa80 40150000 40151000 73 /lib/libnss_files-2.1.1.so
c0d1fb00 40151000 4015a000 75 /lib/libnss_nisplus-2.1.1.so
c5f754e0 4015a000 4015b000 73 /lib/libnss_nisplus-2.1.1.so
c0d1fec0 4015b000 4016d000 75 /lib/libnsl-2.1.1.so
c5f75460 4016d000 4016e000 73 /lib/libnsl-2.1.1.so
c5f75420 4016e000 40170000 73
c5f753e0 40170000 40178000 75 /lib/libnss_nis-2.1.1.so
c5f753a0 40178000 40179000 73 /lib/libnss_nis-2.1.1.so
c0d1f240 bfffc000 c0000000 177
Display the virtual memory data along with page translations for PID 386:
crash> vm -p 386
PID: 386 TASK: c11cc000 CPU: 0 COMMAND: "atd"
MM PGD RSS TOTAL_VM
c7e30560 c10e5000 104k 1112k
VMA START END FLAGS FILE
c0fbe6a0 8048000 804b000 1875 /usr/sbin/atd
VIRTUAL PHYSICAL
8048000 20e1000
8049000 17c6000
804a000 1f6f000
VMA START END FLAGS FILE
c61e0ba0 804b000 804d000 1873 /usr/sbin/atd
VIRTUAL PHYSICAL
804b000 254d000
804c000 6a9c000
VMA START END FLAGS FILE
c61e04e0 804d000 8050000 77
VIRTUAL PHYSICAL
804d000 219d000
804e000 2617000
804f000 SWAP: /dev/sda8 OFFSET: 24225
VMA START END FLAGS FILE
c61e0720 40000000 40012000 875 /lib/ld-2.1.1.so
VIRTUAL PHYSICAL
40000000 FILE: /lib/ld-2.1.1.so OFFSET: 0
40001000 FILE: /lib/ld-2.1.1.so OFFSET: 1000
40002000 FILE: /lib/ld-2.1.1.so OFFSET: 2000
40003000 FILE: /lib/ld-2.1.1.so OFFSET: 3000
40004000 FILE: /lib/ld-2.1.1.so OFFSET: 4000
40005000 FILE: /lib/ld-2.1.1.so OFFSET: 5000
...
Although the -R option is typically invoked from "foreach vm", it can be
executed directly. This example displays all VM areas with vm_flags of 75:
crash> vm -R 75
PID: 694 TASK: c0c76000 CPU: 1 COMMAND: "crash"
MM PGD RSS TOTAL_VM
c6c43110 c0fe9000 8932k 10720k
VMA START END FLAGS FILE
c322c0d0 40019000 4004a000 75 /usr/lib/libncurses.so.4.2
c67537c0 40056000 40071000 75 /lib/libm-2.1.1.so
c6753d00 40072000 40074000 75 /lib/libdl-2.1.1.so
c6753540 40075000 40081000 75 /usr/lib/libz.so.1.1.3
c6753740 40085000 4016b000 75 /lib/libc-2.1.1.so
One reason to use -R directly is to pare down the output associated with
the -p option on a task with a huge address space. This example displays
the page data associated with virtual address 40121000:
crash> vm -R 40121000
PID: 694 TASK: c0c76000 CPU: 0 COMMAND: "crash"
MM PGD RSS TOTAL_VM
c6c43110 c0fe9000 8928k 10720k
VMA START END FLAGS FILE
c6753740 40085000 4016b000 75 /lib/libc-2.1.1.so
VIRTUAL PHYSICAL
40121000 FILE: /lib/libc-2.1.1.so OFFSET: 9c000
Display the mm_struct for PID 4777:
crash> vm -m 4777
PID: 4777 TASK: c0896000 CPU: 0 COMMAND: "bash"
struct mm_struct {
mmap = 0xc6caa1c0,
mmap_avl = 0x0,
mmap_cache = 0xc6caabc0,
pgd = 0xc100a000,
count = {
counter = 0x1
},
map_count = 0x14,
mmap_sem = {
count = {
counter = 0x1
},
waking = 0x0,
wait = 0x0
},
context = 0x0,
start_code = 0x8048000,
end_code = 0x809c6f7,
start_data = 0x0,
end_data = 0x80a2090,
start_brk = 0x80a5420,
brk = 0x80b9000,
start_stack = 0xbffff9d0,
arg_start = 0xbffffad1,
arg_end = 0xbffffad7,
env_start = 0xbffffad7,
env_end = 0xbffffff2,
rss = 0xf6,
total_vm = 0x1a3,
locked_vm = 0x0,
def_flags = 0x0,
cpu_vm_mask = 0x0,
swap_cnt = 0x23d,
swap_address = 0x0,
segments = 0x0
}
Display all of the vm_area_structs for task c47d4000:
crash> vm -v c47d4000
PID: 4971 TASK: c47d4000 CPU: 1 COMMAND: "login"
struct vm_area_struct {
vm_mm = 0xc4b0d200,
vm_start = 0x8048000,
vm_end = 0x804d000,
vm_next = 0xc3e3abd0,
vm_page_prot = {
pgprot = 0x25
},
vm_flags = 0x1875,
vm_avl_height = 0x1,
vm_avl_left = 0x0,
vm_avl_right = 0x0,
vm_next_share = 0x0,
vm_pprev_share = 0xc3e3abf0,
vm_ops = 0xc02392a0,
vm_offset = 0x0,
vm_file = 0xc1e23660,
vm_pte = 0x0
}
struct vm_area_struct {
vm_mm = 0xc4b0d200,
vm_start = 0x804d000,
vm_end = 0x804e000,
vm_next = 0xc3e3a010,
vm_page_prot = {
pgprot = 0x25
},
vm_flags = 0x1873,
vm_avl_height = 0x2,
vm_avl_left = 0xc3e3a810,
vm_avl_right = 0xc3e3a010,
vm_next_share = 0xc3e3a810,
vm_pprev_share = 0xc3699c14
...
Translate a FLAGS value:
crash> vm -f 3875
3875: (READ|EXEC|MAYREAD|MAYWRITE|MAYEXEC|DENYWRITE|EXECUTABLE|LOCKED)
Display the page translations of the VM area at address f5604f2c:
crash> vm -P f5604f2c
PID: 5508 TASK: f56a9570 CPU: 0 COMMAND: "crond"
VMA START END FLAGS FILE
f5604f2c f5b000 f67000 8000075 /lib/libnss_files-2.12.so
VIRTUAL PHYSICAL
f5b000 3fec1000
f5c000 3d3a4000
f5d000 FILE: /lib/libnss_files-2.12.so OFFSET: 2000
f5e000 FILE: /lib/libnss_files-2.12.so OFFSET: 3000
f5f000 FILE: /lib/libnss_files-2.12.so OFFSET: 4000
f60000 3fd31000
f61000 3fd32000
f62000 FILE: /lib/libnss_files-2.12.so OFFSET: 7000
f63000 FILE: /lib/libnss_files-2.12.so OFFSET: 8000
f64000 3ff35000
f65000 FILE: /lib/libnss_files-2.12.so OFFSET: a000
f66000 FILE: /lib/libnss_files-2.12.so OFFSET: b000
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