Prakash Sangappa 2d6d6f5a09 mm: userfaultfd: add feature to request for a signal delivery ... In some cases, userfaultfd mechanism should just deliver a SIGBUS signal to the faulting process, instead of the page-fault event. Dealing with page-fault event using a monitor thread can be an overhead in these cases. For example applications like the database could use the signaling mechanism for robustness purpose. Database uses hugetlbfs for performance reason. Files on hugetlbfs filesystem are created and huge pages allocated using fallocate() API. Pages are deallocated/freed using fallocate() hole punching support. These files are mmapped and accessed by many processes as shared memory. The database keeps track of which offsets in the hugetlbfs file have pages allocated. Any access to mapped address over holes in the file, which can occur due to bugs in the application, is considered invalid and expect the process to simply receive a SIGBUS. However, currently when a hole in the file is accessed via the mapped address, kernel/mm attempts to automatically allocate a page at page fault time, resulting in implicitly filling the hole in the file. This may not be the desired behavior for applications like the database that want to explicitly manage page allocations of hugetlbfs files. Using userfaultfd mechanism with this support to get a signal, database application can prevent pages from being allocated implicitly when processes access mapped address over holes in the file. This patch adds UFFD_FEATURE_SIGBUS feature to userfaultfd mechnism to request for a SIGBUS signal. See following for previous discussion about the database requirement leading to this proposal as suggested by Andrea. http://www.spinics.net/lists/linux-mm/msg129224.html Link: http://lkml.kernel.org/r/1501552446-748335-2-git-send-email-prakash.sangappa@oracle.com Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2017-09-06 17:27:29 -07:00
..
9p	fscache: remove unused ->now_uncached callback	2017-09-06 17:27:26 -07:00
adfs
affs	affs: Implement show_options	2017-07-11 06:06:17 -04:00
afs	fscache: remove unused ->now_uncached callback	2017-09-06 17:27:26 -07:00
autofs4	Fix up over-eager 'wait_queue_t' renaming	2017-07-10 11:40:19 -07:00
befs	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
bfs	bfs: fix sanity checks for empty files	2017-07-12 16:26:00 -07:00
btrfs	Btrfs: fix blk_status_t/errno confusion	2017-08-24 17:19:02 +02:00
cachefiles	sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming	2017-06-20 12:19:14 +02:00
ceph	fscache: remove unused ->now_uncached callback	2017-09-06 17:27:26 -07:00
cifs	fscache: remove unused ->now_uncached callback	2017-09-06 17:27:26 -07:00
coda	fs: implement vfs_iter_write using do_iter_write	2017-06-29 17:49:23 -04:00
configfs	configfs: Introduce config_item_get_unless_zero()	2017-06-12 13:20:20 +02:00
cramfs
crypto	The first major feature for ext4 this merge window is the largedir	2017-07-09 09:31:22 -07:00
debugfs	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
devpts	pty: Repair TIOCGPTPEER	2017-08-24 13:23:03 -07:00
dlm
ecryptfs	ecryptfs: Convert to separately allocated bdi	2017-04-20 12:09:55 -06:00
efivarfs	VFS: Kill off s_options and helpers	2017-07-11 06:09:21 -04:00
efs
exofs	mm: drop "wait" parameter from write_one_page()	2017-07-05 18:44:22 -04:00
exportfs
ext2	dax: use common 4k zero page for dax mmap reads	2017-09-06 17:27:24 -07:00
ext4	mm: remove nr_pages argument from pagevec_lookup{,_range}()	2017-09-06 17:27:27 -07:00
f2fs	f2fs: avoid cpu lockup	2017-07-17 19:23:18 -07:00
fat
freevxfs
fscache	mm: remove nr_pages argument from pagevec_lookup{,_range}()	2017-09-06 17:27:27 -07:00
fuse	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse	2017-08-11 11:20:48 -07:00
gfs2	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
hfs	fs: semove set but not checked AOP_FLAG_UNINTERRUPTIBLE flag	2017-05-08 17:15:14 -07:00
hfsplus	hfsplus: Don't clear SGID when inheriting ACLs	2017-07-18 18:23:39 +02:00
hostfs
hpfs
hugetlbfs	mm: remove nr_pages argument from pagevec_lookup{,_range}()	2017-09-06 17:27:27 -07:00
isofs	isofs: Fix off-by-one in 'session' mount option parsing	2017-07-18 12:33:16 +02:00
jbd2	Writeback error handling fixes (pile #2)	2017-07-07 19:38:17 -07:00
jffs2	jffs2: fix spelling mistake: "requestied" -> "requested"	2017-04-19 11:35:55 -07:00
jfs	jfs should use MAX_LFS_FILESIZE when calculating s_maxbytes	2017-08-31 17:02:21 -07:00
kernfs	kernfs: Clarify lockdep name for kn->count	2017-08-28 16:50:15 +02:00
lockd	sunrpc: mark all struct svc_version instances as const	2017-07-13 15:58:03 -04:00
minix	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-08 10:50:54 -07:00
ncpfs	mm: per-cgroup memory reclaim stats	2017-07-06 16:24:35 -07:00
nfs	fscache: remove unused ->now_uncached callback	2017-09-06 17:27:26 -07:00
nfs_common
nfsd	annotate RWF_... flags	2017-08-31 17:32:38 -04:00
nilfs2	mm: remove nr_pages argument from pagevec_lookup{,_range}()	2017-09-06 17:27:27 -07:00
nls
notify	dentry name snapshots	2017-07-07 20:09:10 -04:00
ntfs	ntfs: Use ERR_CAST() to avoid cross-structure cast	2017-05-28 10:11:48 -07:00
ocfs2	ocfs2: clean up some dead code	2017-09-06 17:27:24 -07:00
omfs	omfs: Implement show_options	2017-07-06 03:31:46 -04:00
openpromfs
orangefs	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
overlayfs	overlayfs, locking: Remove smp_mb__before_spinlock() usage	2017-08-10 12:29:02 +02:00
proc	mm: rename global_page_state to global_zone_page_state	2017-09-06 17:27:29 -07:00
pstore	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
qnx4
qnx6
quota	quota: correct space limit check	2017-08-07 16:51:28 +02:00
ramfs	mm: make pagevec_lookup() update index	2017-09-06 17:27:26 -07:00
reiserfs	reiserfs: preserve i_mode if __reiserfs_set_acl() fails	2017-07-18 11:24:08 +02:00
romfs
squashfs
sysfs
sysv	mm: drop "wait" parameter from write_one_page()	2017-07-05 18:44:22 -04:00
tracefs	VFS: Don't use save/replace_mount_options if not using generic_show_options	2017-07-06 03:31:46 -04:00
ubifs	ubifs: Set double hash cookie also for RENAME_EXCHANGE	2017-07-14 22:50:57 +02:00
udf	udf: Convert udf_disk_stamp_to_time() to use mktime64()	2017-06-14 11:21:02 +02:00
ufs	Writeback error handling fixes (pile #1)	2017-07-07 18:39:15 -07:00
xfs	dax: use common 4k zero page for dax mmap reads	2017-09-06 17:27:24 -07:00
aio.c	fs: add O_DIRECT and aio support for sending down write life time hints	2017-06-27 12:05:36 -06:00
anon_inodes.c
attr.c
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c	x86/elf: Remove the unnecessary ADDR_NO_RANDOMIZE checks	2017-08-16 20:32:02 +02:00
binfmt_em86.c
binfmt_flat.c	binfmt_flat: Use %u to format u32	2017-07-16 09:24:05 -07:00
binfmt_misc.c	fs: constify tree_descr arrays passed to simple_fill_super()	2017-04-26 23:54:06 -04:00
binfmt_script.c
block_dev.c	Writeback error handling fixes (pile #2)	2017-07-07 19:38:17 -07:00
buffer.c	mm: remove nr_pages argument from pagevec_lookup{,_range}()	2017-09-06 17:27:27 -07:00
char_dev.c	char_dev: order /proc/devices by major number	2017-07-17 15:28:50 +02:00
compat_binfmt_elf.c
compat_ioctl.c	Merge branch 'work.__copy_in_user' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-08 10:15:02 -07:00
compat.c
coredump.c
dax.c	dax: initialize variable pfn before using it	2017-09-06 17:27:24 -07:00
dcache.c	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
dcookies.c
direct-io.c	fs: add O_DIRECT and aio support for sending down write life time hints	2017-06-27 12:05:36 -06:00
drop_caches.c
eventfd.c	There has been a fair amount of activity in the docs tree this time	2017-07-03 21:13:25 -07:00
eventpoll.c	epoll: fix race between ep_poll_callback(POLLFREE) and ep_free()/ep_remove()	2017-09-01 13:07:35 -07:00
exec.c	exec: Limit arg stack to at most 75% of _STK_LIM	2017-07-07 20:05:08 -07:00
fcntl.c	vfs: fix flock compat thinko	2017-07-07 13:48:18 -07:00
fhandle.c
file_table.c	fs: new infrastructure for writeback error handling and reporting	2017-07-06 07:02:25 -04:00
file.c	fs/file.c: replace alloc_fdmem() with kvmalloc() alternative	2017-07-06 16:24:30 -07:00
filesystems.c	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
fs_pin.c	sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming	2017-06-20 12:19:14 +02:00
fs_struct.c
fs-writeback.c	writeback: rework wb_[dec|inc]_stat family of functions	2017-07-12 16:26:05 -07:00
inode.c	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-08 10:50:54 -07:00
internal.h	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-05-09 09:12:53 -07:00
ioctl.c
iomap.c	iomap: fix integer truncation issues in the zeroing and dirtying helpers	2017-08-11 16:56:33 -07:00
Kconfig	fs/Kconfig: kill CONFIG_PERCPU_RWSEM some more	2017-07-12 16:26:00 -07:00
Kconfig.binfmt
libfs.c	fs: convert __generic_file_fsync to use errseq_t based reporting	2017-07-06 07:02:29 -04:00
locks.c	fs/locks: pass kernel struct flock to fcntl_getlk/setlk	2017-05-27 06:07:19 -04:00
Makefile
mbcache.c	ext4: xattr inode deduplication	2017-06-22 11:44:55 -04:00
mount.h	Now that IPC and other changes have landed, enable manual markings for	2017-07-19 08:55:18 -07:00
mpage.c	There has been a fair amount of activity in the docs tree this time	2017-07-03 21:13:25 -07:00
namei.c	Now that IPC and other changes have landed, enable manual markings for	2017-07-19 08:55:18 -07:00
namespace.c	Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-15 12:00:42 -07:00
no-block.c
nsfs.c	VFS: Provide empty name qstr	2017-07-06 03:27:09 -04:00
open.c	Writeback error handling fixes (pile #2)	2017-07-07 19:38:17 -07:00
pipe.c	VFS: Provide empty name qstr	2017-07-06 03:27:09 -04:00
pnode.c	mnt: Make propagate_umount less slow for overlapping mount propagation trees	2017-05-23 08:41:17 -05:00
pnode.h
posix_acl.c
proc_namespace.c
read_write.c	annotate RWF_... flags	2017-08-31 17:32:38 -04:00
readdir.c
select.c	fs/select: Fix memory corruption in compat_get_fd_set()	2017-08-28 16:09:19 -07:00
seq_file.c	mm: introduce kv[mz]alloc helpers	2017-05-08 17:15:12 -07:00
signalfd.c	sched/wait: Rename wait_queue_t => wait_queue_entry_t	2017-06-20 12:18:27 +02:00
splice.c	fs: implement vfs_iter_write using do_iter_write	2017-06-29 17:49:23 -04:00
stack.c
stat.c	ufs: restore maintaining ->i_blocks	2017-06-09 16:28:01 -04:00
statfs.c	Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2017-07-08 10:50:54 -07:00
super.c	VFS: Kill off s_options and helpers	2017-07-11 06:09:21 -04:00
sync.c	fs/sync.c: remove unnecessary NULL f_mapping check in sync_file_range	2017-09-06 17:27:28 -07:00
timerfd.c	timerfd: Use get_itimerspec64() and put_itimerspec64()	2017-06-30 04:14:38 -04:00
userfaultfd.c	mm: userfaultfd: add feature to request for a signal delivery	2017-09-06 17:27:29 -07:00
utimes.c
xattr.c	treewide: use kv[mz]alloc* rather than opencoded variants	2017-05-08 17:15:13 -07:00