xmalloc subcommand
The xmalloc subcommand displays memory allocation information, finds the memory location of any heap record using the page index or finds the heap record using the allocated memory location.
Format
xmalloc [-s [effectiveaddress]] [-h [effectiveaddress]] [[-l] -f] [[-l] -a] [[-l] -p page] [-d [effectiveaddress]] [-v] [[-q] -u [size]] [-S] [effectiveaddress] [-H heap_addr]
Parameters
| Item | Description |
|---|---|
| -s | Displays allocation records matching the value of the effectiveaddress parameter. If the effectiveaddress parameter is not specified, the value of the Debug_addr symbol is used. |
| -h | Displays free list records matching effectiveaddress. If effectiveaddress is not specified, the value of the Debug_addr symbol is used. |
| -l | Enables verbose output. Applicable only with the -f, -a, and -p flags. |
| -f | Displays records on the free list, from the first freed record to the last freed record. |
| -a | Displays allocation records. |
| -p page | Displays page information for the specified page. The page number is a hexadecimal value. |
| -d | Displays the allocation record hash chain associated with the record hash value for the effectiveaddress parameter. If the effectiveaddress parameter is not specified, the value of the Debug_addr symbol is used. |
| -v | Verifies allocation trailers for allocated records and verifies free fill patterns for free records. |
| -q | Indicates that allocations should not be separated into size groups. |
| -u | Displays heap statistics. |
| size | Specifies the largest size allocation reported. |
| -S | Displays heap locks and per-processor lists.
Note: The per-processor lists are only used for the kernel heaps.
|
| effectiveaddress | Specifies the effective address for which information is to be displayed. Use symbols, hexadecimal values, or hexadecimal expressions to specify the effective address. |
| -H heap_addr | Specifies the effective address of the heap for which information is displayed. If the -H parameter is not specified, information is displayed for the kernel heap. The -H parameter can be supplied with other xmalloc parameters. Use symbols, hexadecimal values, or hexadecimal expressions to specify the effective address. |
Other than the -u parameter, these parameters require that the Memory Overlay Detection System (MODS) is active. If parameters require a memory address and no value is specified, the value of the Debug_addr symbol is used. If a system crash is caused by detection of a problem within MODS, this value is updated by MODS. The default heap reported on is the kernel heap.
Other
xm
Examples
The following is an example of how to use the xm alias of the xmalloc subcommand:
(0)> stat
RS6K_SMP_MCA POWER_PC POWER_604 machine with 8 processor(s)
.......... SYSTEM STATUS
sysname... AIX nodename.. jumbo32
release... 3 version... 4
machine... 00920312A0 nid....... 920312A0
time of crash: Fri Jul 11 08:07:01 1997
age of system: 1 day, 20 hr., 31 min., 17 sec.
.......... PANIC STRING
Memdbg: *w == pat
(0)> xm -s //Display debug xmalloc status
Debug kernel error message: The xmfree service has found data written beyond the
end of the memory buffer that is being freed.
Address at fault was 0x09410200
(0)> xm -h 0x09410200 //Display debug xmalloc records associated with addr
0B78DAB0: addr......... 09410200 req_size..... 128 freed unpinned
0B78DAB0: pid.......... 00043158 comm......... bcross
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00235CD4(.dlistadd+000040) 00234F04(.setbitmaps+0001BC)
00235520(.newblk+00006C) 00236894(.finicom+0001A4)
0B645120: addr......... 09410200 req_size..... 128 freed unpinned
0B645120: pid.......... 0007DCAC comm......... bcross
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00235CD4(.dlistadd+000040) 00236614(.logdfree+0001E8)
00236574(.logdfree+000148) 00236720(.finicom+000030)
0B7A3750: addr......... 09410200 req_size..... 128 freed unpinned
0B7A3750: pid.......... 000010BA comm......... syncd
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00235CD4(.dlistadd+000040) 00234F04(.setbitmaps+0001BC)
00235520(.newblk+00006C) 00236894(.finicom+0001A4)
0B52B330: addr......... 09410200 req_size..... 128 freed unpinned
0B52B330: pid.......... 00058702 comm......... bcross
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00235CD4(.dlistadd+000040) 00236698(.logdfree+00026C)
00236510(.logdfree+0000E4) 00236720(.finicom+000030)
07A33840: addr......... 09410200 req_size..... 133 freed unpinned
07A33840: pid.......... 00042C24 comm......... ksh
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00271F28(.ld_pathopen+000160) 00271D24(.ld_pathclear+00008C)
0027FB6C(.ld_getlib+000074) 002ABF04(.ld_execload+00075C)
0B796480: addr......... 09410200 req_size..... 133 freed unpinned
0B796480: pid.......... 0005C2E0 comm......... ksh
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00271F28(.ld_pathopen+000160) 00271D24(.ld_pathclear+00008C)
0027FB6C(.ld_getlib+000074) 002ABF04(.ld_execload+00075C)
07A31420: addr......... 09410200 req_size..... 135 freed unpinned
07A31420: pid.......... 0007161A comm......... ksh
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00271F28(.ld_pathopen+000160) 00271D24(.ld_pathclear+00008C)
0027FB6C(.ld_getlib+000074) 002ABF04(.ld_execload+00075C)
07A38630: addr......... 09410200 req_size..... 125 freed unpinned
07A38630: pid.......... 0001121E comm......... ksh
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00271F28(.ld_pathopen+000160) 00271D24(.ld_pathclear+00008C)
0027FB6C(.ld_getlib+000074) 002ABF04(.ld_execload+00075C)
07A3D240: addr......... 09410200 req_size..... 133 freed unpinned
07A3D240: pid.......... 0000654C comm......... ksh
Trace during xmalloc() Trace during xmfree()
002329E4(.xmalloc+0000A8) 002328F0(.xmfree+0000FC)
00271F28(.ld_pathopen+000160) 00271D24(.ld_pathclear+00008C)
0027FB6C(.ld_getlib+000074) 002ABF04(.ld_execload+00075C)
(0)> heap
...
Heap Alloc list
... 0FFC41B0 pageno 00000007 pages.type.. 01 allocrange offset... NO_PAGE
... 0FFC41B4 pageno 00000008 pages.type.. 06 allocsize size..... 00001E00
... 0FFCB9AC pageno 00001E06 pages.type.. 07 allocrangeend offset... 00000007
... 0FFCB9B0 pageno 00001E07 pages.type.. 01 allocrange offset... NO_PAGE
... 0FFCB9B4 pageno 00001E08 pages.type.. 06 allocsize size..... 00001E00
... 0FFD31AC pageno 00003C06 pages.type.. 07 allocrangeend offset... 00001E07
... 0FFD31B4 pageno 00003C08 pages.type.. 01 allocrange offset... 00003C42
... 0FFD31B8 pageno 00003C09 pages.type.. 06 allocsize size..... 00000002
... 0FFD31C4 pageno 00003C0C pages.type.. 01 allocrange offset... NO_PAGE
... 0FFD31C8 pageno 00003C0D pages.type.. 06 allocsize size..... 00000009
... 0FFD31E4 pageno 00003C14 pages.type.. 07 allocrangeend offset... 00003C0C
...
(0)> xm -l -p 00001E07 //how to find memory address of heap index 00001E07
type..................... 1 (P_allocrange)
page_addr................ 02F82000 pinned................... 0
size..................... 00000000 offset................... 00FFFFFF
page_descriptor_address.. 0FFCB9B0
(0)> xm -l 02F82000 //how to find page index in kernel heap of 02F82000
P_allocrange (range of 2 or more allocated full pages)
page........... 00001E07 start.......... 02F82000 page_cnt....... 00001E00
allocated_size. 01E00000 pinned......... unknown
(0)> xm -l -p 00003C08 //how to find memory address of heap index 00003C08
type..................... 1 (P_allocrange)
page_addr................ 04D83000 pinned................... 0
size..................... 00000000 offset................... 00003C42
page_descriptor_address.. 0FFD31B4
(0)> xm -l 04D83000 //how to find page index in kernel heap of 04D83000
P_allocrange (range of 2 or more allocated full pages)
page........... 00003C08 start.......... 04D83000 page_cnt....... 00000002
allocated_size. 00002000 pinned......... unknown