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Diffstat (limited to 'Documentation/filesystems/proc.txt')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 1e4a6cc1b6ea..402ab99e409f 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1605,16 +1605,16 @@ Documentation/accounting. --------------------------------------------------------------- When a process is dumped, all anonymous memory is written to a core file as long as the size of the core file isn't limited. But sometimes we don't want -to dump some memory segments, for example, huge shared memory. Conversely, -sometimes we want to save file-backed memory segments into a core file, not -only the individual files. +to dump some memory segments, for example, huge shared memory or DAX. +Conversely, sometimes we want to save file-backed memory segments into a core +file, not only the individual files. /proc/<pid>/coredump_filter allows you to customize which memory segments will be dumped when the <pid> process is dumped. coredump_filter is a bitmask of memory types. If a bit of the bitmask is set, memory segments of the corresponding memory type are dumped, otherwise they are not dumped. -The following 7 memory types are supported: +The following 9 memory types are supported: - (bit 0) anonymous private memory - (bit 1) anonymous shared memory - (bit 2) file-backed private memory @@ -1623,20 +1623,22 @@ The following 7 memory types are supported: effective only if the bit 2 is cleared) - (bit 5) hugetlb private memory - (bit 6) hugetlb shared memory + - (bit 7) DAX private memory + - (bit 8) DAX shared memory Note that MMIO pages such as frame buffer are never dumped and vDSO pages are always dumped regardless of the bitmask status. - Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only - effected by bit 5-6. + Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is + only affected by bit 5-6, and DAX is only affected by bits 7-8. -Default value of coredump_filter is 0x23; this means all anonymous memory -segments and hugetlb private memory are dumped. +The default value of coredump_filter is 0x33; this means all anonymous memory +segments, ELF header pages and hugetlb private memory are dumped. If you don't want to dump all shared memory segments attached to pid 1234, -write 0x21 to the process's proc file. +write 0x31 to the process's proc file. - $ echo 0x21 > /proc/1234/coredump_filter + $ echo 0x31 > /proc/1234/coredump_filter When a new process is created, the process inherits the bitmask status from its parent. It is useful to set up coredump_filter before the program runs. |