android_kernel_xiaomi_sm8350/include
KOSAKI Motohiro e575f111dc coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped.  But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g.  vmalloc, sound related).

Thus hugepages are never dumped and it can't be debugged easily.  Many
developers want hugepages to be included into core-dump.

However, We can't read generic VM_RESERVED area because this area is often
IO mapping area.  then these area reading may change device state.  it is
definitly undesiable side-effect.

So adding a hugepage specific bit to the coredump filter is better.  It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.

In additional, libhugetlb use hugetlb private mapping pages as anonymous
page.  Then, hugepage private mapping pages should be core dumped by
default.

Then, /proc/[pid]/core_dump_filter has two new bits.

 - bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
 - bit 6 mean hugetlb shared mapping pages are dumped or not.  (default: no)

I tested by following method.

% ulimit -c unlimited
% ./crash_hugepage  50
% ./crash_hugepage  50  -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage  50
% ./crash_hugepage  50  -p
% ls -lh
% gdb ./crash_hugepage core

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>

#include "hugetlbfs.h"

int main(int argc, char** argv){
	char* p;
	int ch;
	int mmap_flags = MAP_SHARED;
	int fd;
	int nr_pages;

	while((ch = getopt(argc, argv, "p")) != -1) {
		switch (ch) {
		case 'p':
			mmap_flags &= ~MAP_SHARED;
			mmap_flags |= MAP_PRIVATE;
			break;
		default:
			/* nothing*/
			break;
		}
	}
	argc -= optind;
	argv += optind;

	if (argc == 0){
		printf("need # of pages\n");
		exit(1);
	}

	nr_pages = atoi(argv[0]);
	if (nr_pages < 2) {
		printf("nr_pages must >2\n");
		exit(1);
	}

	fd = hugetlbfs_unlinked_fd();
	p = mmap(NULL, nr_pages * gethugepagesize(),
		 PROT_READ|PROT_WRITE, mmap_flags, fd, 0);

	sleep(2);

	*(p + gethugepagesize()) = 1; /* COW */
	sleep(2);

	/* crash! */
	*(int*)0 = 1;

	return 0;
}

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:32 -07:00
..
acpi include: replace __FUNCTION__ with __func__ 2008-10-16 11:21:30 -07:00
asm-arm
asm-cris [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-frv FRV: Switch unaligned access to the packed-struct implementation 2008-10-16 15:06:54 -07:00
asm-generic Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6 2008-10-16 12:40:26 -07:00
asm-h8300 h8300: update timer handler - new files 2008-10-16 11:21:29 -07:00
asm-m32r [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-m68k [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-mn10300 [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-parisc [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-um [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
asm-x86 Merge branch 'kvm-updates/2.6.28' of git://git.kernel.org/pub/scm/linux/kernel/git/avi/kvm 2008-10-16 15:36:00 -07:00
asm-xtensa [PATCH] remove unused ibcs2/PER_SVR4 in SET_PERSONALITY 2008-10-16 15:40:05 +02:00
crypto
drm radeon: fix PCI bus mastering support enables. 2008-10-18 07:10:54 +10:00
keys
linux coredump_filter: add hugepage dumping 2008-10-20 08:52:32 -07:00
math-emu
media V4L/DVB (9276): videobuf-dvb: two functions are now static 2008-10-17 17:39:14 -03:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2008-10-16 11:26:26 -07:00
pcmcia
rdma
rxrpc
scsi [SCSI] iscsi_tcp: return a descriptive error value during connection errors 2008-10-13 09:29:00 -04:00
sound Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2008-10-13 14:03:59 -07:00
video fbdev: allow more chip revisions in Epson s1d13... video driver 2008-10-16 11:21:45 -07:00
xen
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