diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DMA-ISA-LPC.txt | 2 | ||||
| -rw-r--r-- | Documentation/fault-injection/fault-injection.txt | 78 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 6 | ||||
| -rw-r--r-- | Documentation/kdump/kdump.txt | 12 |
4 files changed, 93 insertions, 5 deletions
diff --git a/Documentation/DMA-ISA-LPC.txt b/Documentation/DMA-ISA-LPC.txt index c41331398752..7a065ac4a9d1 100644 --- a/Documentation/DMA-ISA-LPC.txt +++ b/Documentation/DMA-ISA-LPC.txt @@ -42,7 +42,7 @@ requirements you pass the flag GFP_DMA to kmalloc. Unfortunately the memory available for ISA DMA is scarce so unless you allocate the memory during boot-up it's a good idea to also pass -__GFP_REPEAT and __GFP_NOWARN to make the allocator try a bit harder. +__GFP_RETRY_MAYFAIL and __GFP_NOWARN to make the allocator try a bit harder. (This scarcity also means that you should allocate the buffer as early as possible and not release it until the driver is unloaded.) diff --git a/Documentation/fault-injection/fault-injection.txt b/Documentation/fault-injection/fault-injection.txt index 415484f3d59a..192d8cbcc5f9 100644 --- a/Documentation/fault-injection/fault-injection.txt +++ b/Documentation/fault-injection/fault-injection.txt @@ -134,6 +134,22 @@ use the boot option: fail_futex= mmc_core.fail_request=<interval>,<probability>,<space>,<times> +o proc entries + +- /proc/self/task/<current-tid>/fail-nth: + + Write to this file of integer N makes N-th call in the current task fail + (N is 0-based). Read from this file returns a single char 'Y' or 'N' + that says if the fault setup with a previous write to this file was + injected or not, and disables the fault if it wasn't yet injected. + Note that this file enables all types of faults (slab, futex, etc). + This setting takes precedence over all other generic debugfs settings + like probability, interval, times, etc. But per-capability settings + (e.g. fail_futex/ignore-private) take precedence over it. + + This feature is intended for systematic testing of faults in a single + system call. See an example below. + How to add new fault injection capability ----------------------------------------- @@ -278,3 +294,65 @@ allocation failure. # env FAILCMD_TYPE=fail_page_alloc \ ./tools/testing/fault-injection/failcmd.sh --times=100 \ -- make -C tools/testing/selftests/ run_tests + +Systematic faults using fail-nth +--------------------------------- + +The following code systematically faults 0-th, 1-st, 2-nd and so on +capabilities in the socketpair() system call. + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/syscall.h> +#include <fcntl.h> +#include <unistd.h> +#include <string.h> +#include <stdlib.h> +#include <stdio.h> +#include <errno.h> + +int main() +{ + int i, err, res, fail_nth, fds[2]; + char buf[128]; + + system("echo N > /sys/kernel/debug/failslab/ignore-gfp-wait"); + sprintf(buf, "/proc/self/task/%ld/fail-nth", syscall(SYS_gettid)); + fail_nth = open(buf, O_RDWR); + for (i = 0;; i++) { + sprintf(buf, "%d", i); + write(fail_nth, buf, strlen(buf)); + res = socketpair(AF_LOCAL, SOCK_STREAM, 0, fds); + err = errno; + read(fail_nth, buf, 1); + if (res == 0) { + close(fds[0]); + close(fds[1]); + } + printf("%d-th fault %c: res=%d/%d\n", i, buf[0], res, err); + if (buf[0] != 'Y') + break; + } + return 0; +} + +An example output: + +0-th fault Y: res=-1/23 +1-th fault Y: res=-1/23 +2-th fault Y: res=-1/23 +3-th fault Y: res=-1/12 +4-th fault Y: res=-1/12 +5-th fault Y: res=-1/23 +6-th fault Y: res=-1/23 +7-th fault Y: res=-1/23 +8-th fault Y: res=-1/12 +9-th fault Y: res=-1/12 +10-th fault Y: res=-1/12 +11-th fault Y: res=-1/12 +12-th fault Y: res=-1/12 +13-th fault Y: res=-1/12 +14-th fault Y: res=-1/12 +15-th fault Y: res=-1/12 +16-th fault N: res=0/12 diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 4cddbce85ac9..adba21b5ada7 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1786,12 +1786,16 @@ pair provide additional information particular to the objects they represent. pos: 0 flags: 02 mnt_id: 9 - tfd: 5 events: 1d data: ffffffffffffffff + tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, 'events' is events mask being watched and the 'data' is data associated with a target [see epoll(7) for more details]. + The 'pos' is current offset of the target file in decimal form + [see lseek(2)], 'ino' and 'sdev' are inode and device numbers + where target file resides, all in hex format. + Fsnotify files ~~~~~~~~~~~~~~ For inotify files the format is the following diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt index 615434d81108..51814450a7f8 100644 --- a/Documentation/kdump/kdump.txt +++ b/Documentation/kdump/kdump.txt @@ -112,8 +112,8 @@ There are two possible methods of using Kdump. 2) Or use the system kernel binary itself as dump-capture kernel and there is no need to build a separate dump-capture kernel. This is possible only with the architectures which support a relocatable kernel. As - of today, i386, x86_64, ppc64, ia64 and arm architectures support relocatable - kernel. + of today, i386, x86_64, ppc64, ia64, arm and arm64 architectures support + relocatable kernel. Building a relocatable kernel is advantageous from the point of view that one does not have to build a second kernel for capturing the dump. But @@ -339,7 +339,7 @@ For arm: For arm64: - Use vmlinux or Image -If you are using a uncompressed vmlinux image then use following command +If you are using an uncompressed vmlinux image then use following command to load dump-capture kernel. kexec -p <dump-capture-kernel-vmlinux-image> \ @@ -361,6 +361,12 @@ to load dump-capture kernel. --dtb=<dtb-for-dump-capture-kernel> \ --append="root=<root-dev> <arch-specific-options>" +If you are using an uncompressed Image, then use following command +to load dump-capture kernel. + + kexec -p <dump-capture-kernel-Image> \ + --initrd=<initrd-for-dump-capture-kernel> \ + --append="root=<root-dev> <arch-specific-options>" Please note, that --args-linux does not need to be specified for ia64. It is planned to make this a no-op on that architecture, but for now |