13 Sep, 2015
2 commits
-
Fix up the writeback plugging introduced in commit d353d7587d02
("writeback: plug writeback at a high level") that then caused problems
due to the unplug happening with a spinlock held.* writeback-plugging:
writeback: plug writeback in wb_writeback() and writeback_inodes_wb()
Revert "writeback: plug writeback at a high level" -
We had to revert the pluggin in writeback_sb_inodes() because the
wb->list_lock is held, but we could easily plug at a higher level before
taking that lock, and unplug after releasing it. This does that.Chris will run performance numbers, just to verify that this approach is
comparable to the alternative (we could just drop and re-take the lock
around the blk_finish_plug() rather than these two commits.I'd have preferred waiting for actual performance numbers before picking
one approach over the other, but I don't want to release rc1 with the
known "sleeping function called from invalid context" issue, so I'll
pick this cleanup version for now. But if the numbers show that we
really want to plug just at the writeback_sb_inodes() level, and we
should just play ugly games with the spinlock, we'll switch to that.Cc: Chris Mason
Cc: Josef Bacik
Cc: Dave Chinner
Cc: Neil Brown
Cc: Jan Kara
Cc: Christoph Hellwig
Signed-off-by: Linus Torvalds
12 Sep, 2015
7 commits
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Merge fourth patch-bomb from Andrew Morton:
- sys_membarier syscall
- seq_file interface changes
- a few misc fixups
* emailed patches from Andrew Morton :
revert "ocfs2/dlm: use list_for_each_entry instead of list_for_each"
mm/early_ioremap: add explicit #include of asm/early_ioremap.h
fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void
selftests: enhance membarrier syscall test
selftests: add membarrier syscall test
sys_membarrier(): system-wide memory barrier (generic, x86)
MODSIGN: fix a compilation warning in extract-cert -
Revert commit f83c7b5e9fd6 ("ocfs2/dlm: use list_for_each_entry instead
of list_for_each").list_for_each_entry() will dereference its `pos' argument, which can be
NULL in dlm_process_recovery_data().Reported-by: Julia Lawall
Reported-by: Fengguang Wu
Cc: Joseph Qi
Cc: Mark Fasheh
Cc: Joel Becker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The seq_ function return values were frequently misused.
See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to
seq_has_overflowed() and make public")All uses of these return values have been removed, so convert the
return types to void.Miscellanea:
o Move seq_put_decimal_ and seq_escape prototypes closer the
other seq_vprintf prototypes
o Reorder seq_putc and seq_puts to return early on overflow
o Add argument names to seq_vprintf and seq_printf
o Update the seq_escape kernel-doc
o Convert a couple of leading spaces to tabs in seq_escapeSigned-off-by: Joe Perches
Cc: Al Viro
Cc: Steven Rostedt
Cc: Mark Brown
Cc: Stephen Rothwell
Cc: Joerg Roedel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This reverts commit d353d7587d02116b9732d5c06615aed75a4d3a47.
Doing the block layer plug/unplug inside writeback_sb_inodes() is
broken, because that function is actually called with a spinlock held:
wb->list_lock, as pointed out by Chris Mason.Chris suggested just dropping and re-taking the spinlock around the
blk_finish_plug() call (the plgging itself can happen under the
spinlock), and that would technically work, but is just disgusting.We do something fairly similar - but not quite as disgusting because we
at least have a better reason for it - in writeback_single_inode(), so
it's not like the caller can depend on the lock being held over the
call, but in this case there just isn't any good reason for that
"release and re-take the lock" pattern.[ In general, we should really strive to avoid the "release and retake"
pattern for locks, because in the general case it can easily cause
subtle bugs when the caller caches any state around the call that
might be invalidated by dropping the lock even just temporarily. ]But in this case, the plugging should be easy to just move up to the
callers before the spinlock is taken, which should even improve the
effectiveness of the plug. So there is really no good reason to play
games with locking here.I'll send off a test-patch so that Dave Chinner can verify that that
plug movement works. In the meantime this just reverts the problematic
commit and adds a comment to the function so that we hopefully don't
make this mistake again.Reported-by: Chris Mason
Cc: Josef Bacik
Cc: Dave Chinner
Cc: Neil Brown
Cc: Jan Kara
Cc: Christoph Hellwig
Signed-off-by: Linus Torvalds -
Pull btrfs cleanups and fixes from Chris Mason:
"These are small cleanups, and also some fixes for our async worker
thread initialization.I was having some trouble testing these, but it ended up being a
combination of changing around my test servers and a shiny new
schedule while atomic from the new start/finish_plug in
writeback_sb_inodes().That one only hits on btrfs raid5/6 or MD raid10, and if I wasn't
changing a bunch of things in my test setup at once it would have been
really clear. Fix for writeback_sb_inodes() on the way as well"* 'for-linus-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: cleanup: remove unnecessary check before btrfs_free_path is called
btrfs: async_thread: Fix workqueue 'max_active' value when initializing
btrfs: Add raid56 support for updating num_tolerated_disk_barrier_failures in btrfs_balance
btrfs: Cleanup for btrfs_calc_num_tolerated_disk_barrier_failures
btrfs: Remove noused chunk_tree and chunk_objectid from scrub_enumerate_chunks and scrub_chunk
btrfs: Update out-of-date "skip parity stripe" comment -
Pull Ceph update from Sage Weil:
"There are a few fixes for snapshot behavior with CephFS and support
for the new keepalive protocol from Zheng, a libceph fix that affects
both RBD and CephFS, a few bug fixes and cleanups for RBD from Ilya,
and several small fixes and cleanups from Jianpeng and others"* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
ceph: improve readahead for file holes
ceph: get inode size for each append write
libceph: check data_len in ->alloc_msg()
libceph: use keepalive2 to verify the mon session is alive
rbd: plug rbd_dev->header.object_prefix memory leak
rbd: fix double free on rbd_dev->header_name
libceph: set 'exists' flag for newly up osd
ceph: cleanup use of ceph_msg_get
ceph: no need to get parent inode in ceph_open
ceph: remove the useless judgement
ceph: remove redundant test of head->safe and silence static analysis warnings
ceph: fix queuing inode to mdsdir's snaprealm
libceph: rename con_work() to ceph_con_workfn()
libceph: Avoid holding the zero page on ceph_msgr_slab_init errors
libceph: remove the unused macro AES_KEY_SIZE
ceph: invalidate dirty pages after forced umount
ceph: EIO all operations after forced umount -
Pull GFS2 updates from Bob Peterson:
"Here is a list of patches we've accumulated for GFS2 for the current
upstream merge window. This time we've only got six patches, many of
which are very small:- three cleanups from Andreas Gruenbacher, including a nice cleanup
of the sequence file code for the sbstats debugfs file.- a patch from Ben Hutchings that changes statistics variables from
signed to unsigned.- two patches from me that increase GFS2's glock scalability by
switching from a conventional hash table to rhashtable"* tag 'gfs2-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
gfs2: A minor "sbstats" cleanup
gfs2: Fix a typo in a comment
gfs2: Make statistics unsigned, suitable for use with do_div()
GFS2: Use resizable hash table for glocks
GFS2: Move glock superblock pointer to field gl_name
gfs2: Simplify the seq file code for "sbstats"
11 Sep, 2015
18 commits
-
Pull blk-cg updates from Jens Axboe:
"A bit later in the cycle, but this has been in the block tree for a a
while. This is basically four patchsets from Tejun, that improve our
buffered cgroup writeback. It was dependent on the other cgroup
changes, but they went in earlier in this cycle.Series 1 is set of 5 patches that has cgroup writeback updates:
- bdi_writeback iteration fix which could lead to some wb's being
skipped or repeated during e.g. sync under memory pressure.- Simplification of wb work wait mechanism.
- Writeback tracepoints updated to report cgroup.
Series 2 is is a set of updates for the CFQ cgroup writeback handling:
cfq has always charged all async IOs to the root cgroup. It didn't
have much choice as writeback didn't know about cgroups and there
was no way to tell who to blame for a given writeback IO.
writeback finally grew support for cgroups and now tags each
writeback IO with the appropriate cgroup to charge it against.This patchset updates cfq so that it follows the blkcg each bio is
tagged with. Async cfq_queues are now shared across cfq_group,
which is per-cgroup, instead of per-request_queue cfq_data. This
makes all IOs follow the weight based IO resource distribution
implemented by cfq.- Switched from GFP_ATOMIC to GFP_NOWAIT as suggested by Jeff.
- Other misc review points addressed, acks added and rebased.
Series 3 is the blkcg policy cleanup patches:
This patchset contains assorted cleanups for blkcg_policy methods
and blk[c]g_policy_data handling.- alloc/free added for blkg_policy_data. exit dropped.
- alloc/free added for blkcg_policy_data.
- blk-throttle's async percpu allocation is replaced with direct
allocation.- all methods now take blk[c]g_policy_data instead of blkcg_gq or
blkcg.And finally, series 4 is a set of patches cleaning up the blkcg stats
handling:blkcg's stats have always been somwhat of a mess. This patchset
tries to improve the situation a bit.- The following patches added to consolidate blkcg entry point and
blkg creation. This is in itself is an improvement and helps
colllecting common stats on bio issue.- per-blkg stats now accounted on bio issue rather than request
completion so that bio based and request based drivers can behave
the same way. The issue was spotted by Vivek.- cfq-iosched implements custom recursive stats and blk-throttle
implements custom per-cpu stats. This patchset make blkcg core
support both by default.- cfq-iosched and blk-throttle keep track of the same stats
multiple times. Unify them"* 'for-4.3/blkcg' of git://git.kernel.dk/linux-block: (45 commits)
blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy
blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/
blkcg: implement interface for the unified hierarchy
blkcg: misc preparations for unified hierarchy interface
blkcg: separate out tg_conf_updated() from tg_set_conf()
blkcg: move body parsing from blkg_conf_prep() to its callers
blkcg: mark existing cftypes as legacy
blkcg: rename subsystem name from blkio to io
blkcg: refine error codes returned during blkcg configuration
blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device()
blkcg: reduce stack usage of blkg_rwstat_recursive_sum()
blkcg: remove cfqg_stats->sectors
blkcg: move io_service_bytes and io_serviced stats into blkcg_gq
blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq
blkcg: make blkcg_[rw]stat per-cpu
blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it
blkcg: consolidate blkg creation in blkcg_bio_issue_check()
blk-throttle: improve queue bypass handling
blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup()
blkcg: inline [__]blkg_lookup()
... -
Merge third patch-bomb from Andrew Morton:
- even more of the rest of MM
- lib/ updates
- checkpatch updates
- small changes to a few scruffy filesystems
- kmod fixes/cleanups
- kexec updates
- a dma-mapping cleanup series from hch
* emailed patches from Andrew Morton : (81 commits)
dma-mapping: consolidate dma_set_mask
dma-mapping: consolidate dma_supported
dma-mapping: cosolidate dma_mapping_error
dma-mapping: consolidate dma_{alloc,free}_noncoherent
dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}
mm: use vma_is_anonymous() in create_huge_pmd() and wp_huge_pmd()
mm: make sure all file VMAs have ->vm_ops set
mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()
mm: mark most vm_operations_struct const
namei: fix warning while make xmldocs caused by namei.c
ipc: convert invalid scenarios to use WARN_ON
zlib_deflate/deftree: remove bi_reverse()
lib/decompress_unlzma: Do a NULL check for pointer
lib/decompressors: use real out buf size for gunzip with kernel
fs/affs: make root lookup from blkdev logical size
sysctl: fix int -> unsigned long assignments in INT_MIN case
kexec: export KERNEL_IMAGE_SIZE to vmcoreinfo
kexec: align crash_notes allocation to make it be inside one physical page
kexec: remove unnecessary test in kimage_alloc_crash_control_pages()
kexec: split kexec_load syscall from kexec core code
... -
With two exceptions (drm/qxl and drm/radeon) all vm_operations_struct
structs should be constant.Signed-off-by: Kirill A. Shutemov
Reviewed-by: Oleg Nesterov
Cc: "H. Peter Anvin"
Cc: Andy Lutomirski
Cc: Dave Hansen
Cc: Ingo Molnar
Cc: Minchan Kim
Cc: Thomas Gleixner
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix the following warnings:
Warning(.//fs/namei.c:2422): No description found for parameter 'nd'
Warning(.//fs/namei.c:2422): Excess function parameter 'nameidata'
description in 'path_mountpoint'Signed-off-by: Masanari Iida
Acked-by: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch resolves https://bugzilla.kernel.org/show_bug.cgi?id=16531.
When logical blkdev size > 512 then sector numbers become larger than the
device can support.Make affs start lookup based on the device's logical sector size instead
of 512.Reported-by: Mark
Suggested-by: Mark
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This introduces a new helper and switches current users to use it. All
patches are compiled tested. kmemleak is tested via its own test suite.This patch (of 6):
The new seq_hex_dump() is a complete analogue of print_hex_dump().
We have few users of this functionality already. It allows to reduce their
codebase.Signed-off-by: Andy Shevchenko
Cc: Alexander Viro
Cc: Joe Perches
Cc: Tadeusz Struk
Cc: Helge Deller
Cc: Ingo Tuchscherer
Cc: Catalin Marinas
Cc: Vladimir Kondratiev
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
On a filesystem like vfat, all files are created with the same owner
and mode independent of who created the file. When a vfat filesystem
is mounted with root as owner of all files and read access for everyone,
root's processes left world-readable coredumps on it (but other
users' processes only left empty corefiles when given write access
because of the uid mismatch).Given that the old behavior was inconsistent and insecure, I don't see
a problem with changing it. Now, all processes refuse to dump core unless
the resulting corefile will only be readable by their owner.Signed-off-by: Jann Horn
Acked-by: Kees Cook
Cc: Al Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
It was possible for an attacking user to trick root (or another user) into
writing his coredumps into an attacker-readable, pre-existing file using
rename() or link(), causing the disclosure of secret data from the victim
process' virtual memory. Depending on the configuration, it was also
possible to trick root into overwriting system files with coredumps. Fix
that issue by never writing coredumps into existing files.Requirements for the attack:
- The attack only applies if the victim's process has a nonzero
RLIMIT_CORE and is dumpable.
- The attacker can trick the victim into coredumping into an
attacker-writable directory D, either because the core_pattern is
relative and the victim's cwd is attacker-writable or because an
absolute core_pattern pointing to a world-writable directory is used.
- The attacker has one of these:
A: on a system with protected_hardlinks=0:
execute access to a folder containing a victim-owned,
attacker-readable file on the same partition as D, and the
victim-owned file will be deleted before the main part of the attack
takes place. (In practice, there are lots of files that fulfill
this condition, e.g. entries in Debian's /var/lib/dpkg/info/.)
This does not apply to most Linux systems because most distros set
protected_hardlinks=1.
B: on a system with protected_hardlinks=1:
execute access to a folder containing a victim-owned,
attacker-readable and attacker-writable file on the same partition
as D, and the victim-owned file will be deleted before the main part
of the attack takes place.
(This seems to be uncommon.)
C: on any system, independent of protected_hardlinks:
write access to a non-sticky folder containing a victim-owned,
attacker-readable file on the same partition as D
(This seems to be uncommon.)The basic idea is that the attacker moves the victim-owned file to where
he expects the victim process to dump its core. The victim process dumps
its core into the existing file, and the attacker reads the coredump from
it.If the attacker can't move the file because he does not have write access
to the containing directory, he can instead link the file to a directory
he controls, then wait for the original link to the file to be deleted
(because the kernel checks that the link count of the corefile is 1).A less reliable variant that requires D to be non-sticky works with link()
and does not require deletion of the original link: link() the file into
D, but then unlink() it directly before the kernel performs the link count
check.On systems with protected_hardlinks=0, this variant allows an attacker to
not only gain information from coredumps, but also clobber existing,
victim-writable files with coredumps. (This could theoretically lead to a
privilege escalation.)Signed-off-by: Jann Horn
Cc: Kees Cook
Cc: Al Viro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix B-tree corruption when a new record is inserted at position 0 in the
node in hfs_brec_insert().This is an identical change to the corresponding hfs b-tree code to Sergei
Antonov's "hfsplus: fix B-tree corruption after insertion at position 0",
to keep similar code paths in the hfs and hfsplus drivers in sync, where
appropriate.Signed-off-by: Hin-Tak Leung
Cc: Sergei Antonov
Cc: Joe Perches
Reviewed-by: Vyacheslav Dubeyko
Cc: Anton Altaparmakov
Cc: Al Viro
Cc: Christoph Hellwig
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Pages looked up by __hfs_bnode_create() (called by hfs_bnode_create() and
hfs_bnode_find() for finding or creating pages corresponding to an inode)
are immediately kmap()'ed and used (both read and write) and kunmap()'ed,
and should not be page_cache_release()'ed until hfs_bnode_free().This patch fixes a problem I first saw in July 2012: merely running "du"
on a large hfsplus-mounted directory a few times on a reasonably loaded
system would get the hfsplus driver all confused and complaining about
B-tree inconsistencies, and generates a "BUG: Bad page state". Most
recently, I can generate this problem on up-to-date Fedora 22 with shipped
kernel 4.0.5, by running "du /" (="/" + "/home" + "/mnt" + other smaller
mounts) and "du /mnt" simultaneously on two windows, where /mnt is a
lightly-used QEMU VM image of the full Mac OS X 10.9:$ df -i / /home /mnt
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/mapper/fedora-root 3276800 551665 2725135 17% /
/dev/mapper/fedora-home 52879360 716221 52163139 2% /home
/dev/nbd0p2 4294967295 1387818 4293579477 1% /mntAfter applying the patch, I was able to run "du /" (60+ times) and "du
/mnt" (150+ times) continuously and simultaneously for 6+ hours.There are many reports of the hfsplus driver getting confused under load
and generating "BUG: Bad page state" or other similar issues over the
years. [1]The unpatched code [2] has always been wrong since it entered the kernel
tree. The only reason why it gets away with it is that the
kmap/memcpy/kunmap follow very quickly after the page_cache_release() so
the kernel has not had a chance to reuse the memory for something else,
most of the time.The current RW driver appears to have followed the design and development
of the earlier read-only hfsplus driver [3], where-by version 0.1 (Dec
2001) had a B-tree node-centric approach to
read_cache_page()/page_cache_release() per bnode_get()/bnode_put(),
migrating towards version 0.2 (June 2002) of caching and releasing pages
per inode extents. When the current RW code first entered the kernel [2]
in 2005, there was an REF_PAGES conditional (and "//" commented out code)
to switch between B-node centric paging to inode-centric paging. There
was a mistake with the direction of one of the REF_PAGES conditionals in
__hfs_bnode_create(). In a subsequent "remove debug code" commit [4], the
read_cache_page()/page_cache_release() per bnode_get()/bnode_put() were
removed, but a page_cache_release() was mistakenly left in (propagating
the "REF_PAGES !REF_PAGE" mistake), and the commented-out
page_cache_release() in bnode_release() (which should be spanned by
!REF_PAGES) was never enabled.References:
[1]:
Michael Fox, Apr 2013
http://www.spinics.net/lists/linux-fsdevel/msg63807.html
("hfsplus volume suddenly inaccessable after 'hfs: recoff %d too large'")Sasha Levin, Feb 2015
http://lkml.org/lkml/2015/2/20/85 ("use after free")https://bugs.launchpad.net/ubuntu/+source/linux/+bug/740814
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1027887
https://bugzilla.kernel.org/show_bug.cgi?id=42342
https://bugzilla.kernel.org/show_bug.cgi?id=63841
https://bugzilla.kernel.org/show_bug.cgi?id=78761[2]:
http://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/\
fs/hfs/bnode.c?id=d1081202f1d0ee35ab0beb490da4b65d4bc763db
commit d1081202f1d0ee35ab0beb490da4b65d4bc763db
Author: Andrew Morton
Date: Wed Feb 25 16:17:36 2004 -0800[PATCH] HFS rewrite
http://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/\
fs/hfsplus/bnode.c?id=91556682e0bf004d98a529bf829d339abb98bbbdcommit 91556682e0bf004d98a529bf829d339abb98bbbd
Author: Andrew Morton
Date: Wed Feb 25 16:17:48 2004 -0800[PATCH] HFS+ support
[3]:
http://sourceforge.net/projects/linux-hfsplus/http://sourceforge.net/projects/linux-hfsplus/files/Linux%202.4.x%20patch/hfsplus%200.1/
http://sourceforge.net/projects/linux-hfsplus/files/Linux%202.4.x%20patch/hfsplus%200.2/http://linux-hfsplus.cvs.sourceforge.net/viewvc/linux-hfsplus/linux/\
fs/hfsplus/bnode.c?r1=1.4&r2=1.5Date: Thu Jun 6 09:45:14 2002 +0000
Use buffer cache instead of page cache in bnode.c. Cache inode extents.[4]:
http://git.kernel.org/cgit/linux/kernel/git/\
stable/linux-stable.git/commit/?id=a5e3985fa014029eb6795664c704953720cc7f7dcommit a5e3985fa014029eb6795664c704953720cc7f7d
Author: Roman Zippel
Date: Tue Sep 6 15:18:47 2005 -0700[PATCH] hfs: remove debug code
Signed-off-by: Hin-Tak Leung
Signed-off-by: Sergei Antonov
Reviewed-by: Anton Altaparmakov
Reported-by: Sasha Levin
Cc: Al Viro
Cc: Christoph Hellwig
Cc: Vyacheslav Dubeyko
Cc: Sougata Santra
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Dan Carpenter discovered a buffer overflow in the Coda file system
readlink code. A userspace file system daemon can return a 4096 byte
result which then triggers a one byte write past the allocated readlink
result buffer.This does not trigger with an unmodified Coda implementation because Coda
has a 1024 byte limit for symbolic links, however other userspace file
systems using the Coda kernel module could be affected.Although this is an obvious overflow, I don't think this has to be handled
as too sensitive from a security perspective because the overflow is on
the Coda userspace daemon side which already needs root to open Coda's
kernel device and to mount the file system before we get to the point that
links can be read.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jan Harkes
Reported-by: Dan Carpenter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Convert from manual allocation/copy_from_user/... to kstrto*() family
which were designed for exactly that.One case can not be converted to kstrto*_from_user() to make code even
more simpler because of whitespace stripping, oh well...Signed-off-by: Alexey Dobriyan
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The proc_subdir_lock spinlock is used to allow only one task to make
change to the proc directory structure as well as looking up information
in it. However, the information lookup part can actually be entered by
more than one task as the pde_get() and pde_put() reference count update
calls in the critical sections are atomic increment and decrement
respectively and so are safe with concurrent updates.The x86 architecture has already used qrwlock which is fair and other
architectures like ARM are in the process of switching to qrwlock. So
unfairness shouldn't be a concern in that conversion.This patch changed the proc_subdir_lock to a rwlock in order to enable
concurrent lookup. The following functions were modified to take a
write lock:
- proc_register()
- remove_proc_entry()
- remove_proc_subtree()The following functions were modified to take a read lock:
- xlate_proc_name()
- proc_lookup_de()
- proc_readdir_de()A parallel /proc filesystem search with the "find" command (1000 threads)
was run on a 4-socket Haswell-EX box (144 threads). Before the patch, the
parallel search took about 39s. After the patch, the parallel find took
only 25s, a saving of about 14s.The micro-benchmark that I used was artificial, but it was used to
reproduce an exit hanging problem that I saw in real application. In
fact, only allow one task to do a lookup seems too limiting to me.Signed-off-by: Waiman Long
Acked-by: "Eric W. Biederman"
Cc: Alexey Dobriyan
Cc: Nicolas Dichtel
Cc: Al Viro
Cc: Scott J Norton
Cc: Douglas Hatch
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, /proc//map_files/ is restricted to CAP_SYS_ADMIN, and is
only exposed if CONFIG_CHECKPOINT_RESTORE is set.Each mapped file region gets a symlink in /proc//map_files/
corresponding to the virtual address range at which it is mapped. The
symlinks work like the symlinks in /proc//fd/, so you can follow them
to the backing file even if that backing file has been unlinked.Currently, files which are mapped, unlinked, and closed are impossible to
stat() from userspace. Exposing /proc//map_files/ closes this
functionality "hole".Not being able to stat() such files makes noticing and explicitly
accounting for the space they use on the filesystem impossible. You can
work around this by summing up the space used by every file in the
filesystem and subtracting that total from what statfs() tells you, but
that obviously isn't great, and it becomes unworkable once your filesystem
becomes large enough.This patch moves map_files/ out from behind CONFIG_CHECKPOINT_RESTORE, and
adjusts the permissions enforced on it as follows:* proc_map_files_lookup()
* proc_map_files_readdir()
* map_files_d_revalidate()Remove the CAP_SYS_ADMIN restriction, leaving only the current
restriction requiring PTRACE_MODE_READ. The information made
available to userspace by these three functions is already
available in /proc/PID/maps with MODE_READ, so I don't see any
reason to limit them any further (see below for more detail).* proc_map_files_follow_link()
This stub has been added, and requires that the user have
CAP_SYS_ADMIN in order to follow the links in map_files/,
since there was concern on LKML both about the potential for
bypassing permissions on ancestor directories in the path to
files pointed to, and about what happens with more exotic
memory mappings created by some drivers (ie dma-buf).In older versions of this patch, I changed every permission check in
the four functions above to enforce MODE_ATTACH instead of MODE_READ.
This was an oversight on my part, and after revisiting the discussion
it seems that nobody was concerned about anything outside of what is
made possible by ->follow_link(). So in this version, I've left the
checks for PTRACE_MODE_READ as-is.[akpm@linux-foundation.org: catch up with concurrent proc_pid_follow_link() changes]
Signed-off-by: Calvin Owens
Reviewed-by: Kees Cook
Cc: Andy Lutomirski
Cc: Cyrill Gorcunov
Cc: Joe Perches
Cc: Kirill A. Shutemov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Reading/writing a /proc/kpage* file may take long on machines with a lot
of RAM installed.Signed-off-by: Vladimir Davydov
Suggested-by: Andres Lagar-Cavilla
Reviewed-by: Andres Lagar-Cavilla
Cc: Minchan Kim
Cc: Raghavendra K T
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Greg Thelen
Cc: Michel Lespinasse
Cc: David Rientjes
Cc: Pavel Emelyanov
Cc: Cyrill Gorcunov
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
As noted by Minchan, a benefit of reading idle flag from /proc/kpageflags
is that one can easily filter dirty and/or unevictable pages while
estimating the size of unused memory.Note that idle flag read from /proc/kpageflags may be stale in case the
page was accessed via a PTE, because it would be too costly to iterate
over all page mappings on each /proc/kpageflags read to provide an
up-to-date value. To make sure the flag is up-to-date one has to read
/sys/kernel/mm/page_idle/bitmap first.Signed-off-by: Vladimir Davydov
Reviewed-by: Andres Lagar-Cavilla
Cc: Minchan Kim
Cc: Raghavendra K T
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Greg Thelen
Cc: Michel Lespinasse
Cc: David Rientjes
Cc: Pavel Emelyanov
Cc: Cyrill Gorcunov
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Knowing the portion of memory that is not used by a certain application or
memory cgroup (idle memory) can be useful for partitioning the system
efficiently, e.g. by setting memory cgroup limits appropriately.
Currently, the only means to estimate the amount of idle memory provided
by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
access bit for all pages mapped to a particular process by writing 1 to
clear_refs, wait for some time, and then count smaps:Referenced. However,
this method has two serious shortcomings:- it does not count unmapped file pages
- it affects the reclaimer logicTo overcome these drawbacks, this patch introduces two new page flags,
Idle and Young, and a new sysfs file, /sys/kernel/mm/page_idle/bitmap.
A page's Idle flag can only be set from userspace by setting bit in
/sys/kernel/mm/page_idle/bitmap at the offset corresponding to the page,
and it is cleared whenever the page is accessed either through page tables
(it is cleared in page_referenced() in this case) or using the read(2)
system call (mark_page_accessed()). Thus by setting the Idle flag for
pages of a particular workload, which can be found e.g. by reading
/proc/PID/pagemap, waiting for some time to let the workload access its
working set, and then reading the bitmap file, one can estimate the amount
of pages that are not used by the workload.The Young page flag is used to avoid interference with the memory
reclaimer. A page's Young flag is set whenever the Access bit of a page
table entry pointing to the page is cleared by writing to the bitmap file.
If page_referenced() is called on a Young page, it will add 1 to its
return value, therefore concealing the fact that the Access bit was
cleared.Note, since there is no room for extra page flags on 32 bit, this feature
uses extended page flags when compiled on 32 bit.[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: kpageidle requires an MMU]
[akpm@linux-foundation.org: decouple from page-flags rework]
Signed-off-by: Vladimir Davydov
Reviewed-by: Andres Lagar-Cavilla
Cc: Minchan Kim
Cc: Raghavendra K T
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Greg Thelen
Cc: Michel Lespinasse
Cc: David Rientjes
Cc: Pavel Emelyanov
Cc: Cyrill Gorcunov
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
/proc/kpagecgroup contains a 64-bit inode number of the memory cgroup each
page is charged to, indexed by PFN. Having this information is useful for
estimating a cgroup working set size.The file is present if CONFIG_PROC_PAGE_MONITOR && CONFIG_MEMCG.
Signed-off-by: Vladimir Davydov
Reviewed-by: Andres Lagar-Cavilla
Cc: Minchan Kim
Cc: Raghavendra K T
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Greg Thelen
Cc: Michel Lespinasse
Cc: David Rientjes
Cc: Pavel Emelyanov
Cc: Cyrill Gorcunov
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
10 Sep, 2015
3 commits
-
Followup to the UFS series - with the way we clear the new blocks (via
buffer cache, possibly on more than a page worth of file) we really
should not insert a reference to new block into inode block tree until
after we'd cleared it.Signed-off-by: Al Viro
Signed-off-by: Linus Torvalds -
Pull cifs updates from Steve French:
"Small cifs fix and a patch for improved debugging"* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Fix use-after-free on mid_q_entry
Update cifs version number
Add way to query server fs info for smb3 -
As part of the v4.3 merge window the DAX code was updated by Matthew and
Kirill to handle PMD pages. Also as part of the v4.3 merge window we
updated the DAX code to do proper PMEM flushing (commit 2765cfbb342c:
"dax: update I/O path to do proper PMEM flushing").The additional code added by the DAX PMD patches also needs to be
updated to properly use the PMEM API. This ensures that after a PMD
fault is handled the zeros written to the newly allocated pages are
durable on the DIMMs.linux/dax.h is included to get rid of a bunch of sparse warnings.
Signed-off-by: Ross Zwisler
Cc: Matthew Wilcox ,
Cc: Dan Williams
Cc: Kirill Shutemov
Signed-off-by: Linus Torvalds
09 Sep, 2015
10 commits
-
When readahead encounters file holes, osd reply returns error -ENOENT,
finish_read() skips adding pages to the the page cache. So readahead
does not work for file holes. The fix is adding zero pages to the
page cache when -ENOENT is returned.Signed-off-by: Yan, Zheng
-
Signed-off-by: Yan, Zheng
-
Merge second patch-bomb from Andrew Morton:
"Almost all of the rest of MM. There was an unusually large amount of
MM material this time"* emailed patches from Andrew Morton : (141 commits)
zpool: remove no-op module init/exit
mm: zbud: constify the zbud_ops
mm: zpool: constify the zpool_ops
mm: swap: zswap: maybe_preload & refactoring
zram: unify error reporting
zsmalloc: remove null check from destroy_handle_cache()
zsmalloc: do not take class lock in zs_shrinker_count()
zsmalloc: use class->pages_per_zspage
zsmalloc: consider ZS_ALMOST_FULL as migrate source
zsmalloc: partial page ordering within a fullness_list
zsmalloc: use shrinker to trigger auto-compaction
zsmalloc: account the number of compacted pages
zsmalloc/zram: introduce zs_pool_stats api
zsmalloc: cosmetic compaction code adjustments
zsmalloc: introduce zs_can_compact() function
zsmalloc: always keep per-class stats
zsmalloc: drop unused variable `nr_to_migrate'
mm/memblock.c: fix comment in __next_mem_range()
mm/page_alloc.c: fix type information of memoryless node
memory-hotplug: fix comments in zone_spanned_pages_in_node() and zone_spanned_pages_in_node()
... -
Pull regmap updates from Mark Brown:
"This has been a busy release for regmap.By far the biggest set of changes here are those from Markus Pargmann
which implement support for block transfers in smbus devices. This
required quite a bit of refactoring but leaves us better able to
handle odd restrictions that controllers may have and with better
performance on smbus.Other new features include:
- Fix interactions with lockdep for nested regmaps (eg, when a device
using regmap is connected to a bus where the bus controller has a
separate regmap). Lockdep's default class identification is too
crude to work without help.- Support for must write bitfield operations, useful for operations
which require writing a bit to trigger them from Kuniori Morimoto.- Support for delaying during register patch application from Nariman
Poushin.- Support for overriding cache state via the debugfs implementation
from Richard Fitzgerald"* tag 'regmap-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap: (25 commits)
regmap: fix a NULL pointer dereference in __regmap_init
regmap: Support bulk reads for devices without raw formatting
regmap-i2c: Add smbus i2c block support
regmap: Add raw_write/read checks for max_raw_write/read sizes
regmap: regmap max_raw_read/write getter functions
regmap: Introduce max_raw_read/write for regmap_bulk_read/write
regmap: Add missing comments about struct regmap_bus
regmap: No multi_write support if bus->write does not exist
regmap: Split use_single_rw internally into use_single_read/write
regmap: Fix regmap_bulk_write for bus writes
regmap: regmap_raw_read return error on !bus->read
regulator: core: Print at debug level on debugfs creation failure
regmap: Fix regmap_can_raw_write check
regmap: fix typos in regmap.c
regmap: Fix integertypes for register address and value
regmap: Move documentation to regmap.h
regmap: Use different lockdep class for each regmap init call
thermal: sti: Add parentheses around bridge->ops->regmap_init call
mfd: vexpress: Add parentheses around bridge->ops->regmap_init call
regmap: debugfs: Fix misuse of IS_ENABLED
... -
This is based on the shmem version, but it has diverged quite a bit. We
have no swap to worry about, nor the new file sealing. Add
synchronication via the fault mutex table to coordinate page faults,
fallocate allocation and fallocate hole punch.What this allows us to do is move physical memory in and out of a
hugetlbfs file without having it mapped. This also gives us the ability
to support MADV_REMOVE since it is currently implemented using
fallocate(). MADV_REMOVE lets madvise() remove pages from the middle of
a hugetlbfs file, which wasn't possible before.hugetlbfs fallocate only operates on whole huge pages.
Based on code by Dave Hansen.
Signed-off-by: Mike Kravetz
Reviewed-by: Naoya Horiguchi
Acked-by: Hillf Danton
Cc: Dave Hansen
Cc: David Rientjes
Cc: Hugh Dickins
Cc: Davidlohr Bueso
Cc: Aneesh Kumar
Cc: Christoph Hellwig
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Modify truncate_hugepages() to take a range of pages (start, end)
instead of simply start. If an end value of LLONG_MAX is passed, the
current "truncate" functionality is maintained. Existing callers are
modified to pass LLONG_MAX as end of range. By keying off end ==
LLONG_MAX, the routine behaves differently for truncate and hole punch.
Page removal is now synchronized with page allocation via faults by
using the fault mutex table. The hole punch case can experience the
rare region_del error and must handle accordingly.Add the routine hugetlb_fix_reserve_counts to fix up reserve counts in
the case where region_del returns an error.Since the routine handles more than just the truncate case, it is
renamed to remove_inode_hugepages(). To be consistent, the routine
truncate_huge_page() is renamed remove_huge_page().Downstream of remove_inode_hugepages(), the routine
hugetlb_unreserve_pages() is also modified to take a range of pages.
hugetlb_unreserve_pages is modified to detect an error from region_del and
pass it back to the caller.Signed-off-by: Mike Kravetz
Reviewed-by: Naoya Horiguchi
Acked-by: Hillf Danton
Cc: Dave Hansen
Cc: David Rientjes
Cc: Hugh Dickins
Cc: Davidlohr Bueso
Cc: Aneesh Kumar
Cc: Christoph Hellwig
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
fallocate hole punch will want to unmap a specific range of pages.
Modify the existing hugetlb_vmtruncate_list() routine to take a
start/end range. If end is 0, this indicates all pages after start
should be unmapped. This is the same as the existing truncate
functionality. Modify existing callers to add 0 as end of range.Since the routine will be used in hole punch as well as truncate
operations, it is more appropriately renamed to hugetlb_vmdelete_list().Signed-off-by: Mike Kravetz
Reviewed-by: Naoya Horiguchi
Acked-by: Hillf Danton
Cc: Dave Hansen
Cc: David Rientjes
Cc: Hugh Dickins
Cc: Davidlohr Bueso
Cc: Aneesh Kumar
Cc: Christoph Hellwig
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
We want to know per-process workingset size for smart memory management
on userland and we use swap(ex, zram) heavily to maximize memory
efficiency so workingset includes swap as well as RSS.On such system, if there are lots of shared anonymous pages, it's really
hard to figure out exactly how many each process consumes memory(ie, rss
+ wap) if the system has lots of shared anonymous memory(e.g, android).This patch introduces SwapPss field on /proc//smaps so we can get
more exact workingset size per process.Bongkyu tested it. Result is below.
1. 50M used swap
SwapTotal: 461976 kB
SwapFree: 411192 kB$ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}';
48236
$ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}';
1411842. 240M used swap
SwapTotal: 461976 kB
SwapFree: 216808 kB$ adb shell cat /proc/*/smaps | grep "SwapPss:" | awk '{sum += $2} END {print sum}';
230315
$ adb shell cat /proc/*/smaps | grep "Swap:" | awk '{sum += $2} END {print sum}';
1387744[akpm@linux-foundation.org: simplify kunmap_atomic() call]
Signed-off-by: Minchan Kim
Reported-by: Bongkyu Kim
Tested-by: Bongkyu Kim
Cc: Hugh Dickins
Cc: Sergey Senozhatsky
Cc: Jonathan Corbet
Cc: Jerome Marchand
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch sets bit 56 in pagemap if this page is mapped only once. It
allows to detect exclusively used pages without exposing PFN:present file exclusive state
0 0 0 non-present
1 1 0 file page mapped somewhere else
1 1 1 file page mapped only here
1 0 0 anon non-CoWed page (shared with parent/child)
1 0 1 anon CoWed page (or never forked)CoWed pages in (MAP_FILE | MAP_PRIVATE) areas are anon in this context.
MMap-exclusive bit doesn't reflect potential page-sharing via swapcache:
page could be mapped once but has several swap-ptes which point to it.
Application could detect that by swap bit in pagemap entry and touch that
pte via /proc/pid/mem to get real information.See http://lkml.kernel.org/r/CAEVpBa+_RyACkhODZrRvQLs80iy0sqpdrd0AaP_-tgnX3Y9yNQ@mail.gmail.com
Requested by Mark Williamson.
[akpm@linux-foundation.org: fix spello]
Signed-off-by: Konstantin Khlebnikov
Reviewed-by: Mark Williamson
Tested-by: Mark Williamson
Reviewed-by: Naoya Horiguchi
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch makes pagemap readable for normal users and hides physical
addresses from them. For some use-cases PFN isn't required at all.See http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@shutemov.name
Fixes: ab676b7d6fbf ("pagemap: do not leak physical addresses to non-privileged userspace")
Signed-off-by: Konstantin Khlebnikov
Cc: Naoya Horiguchi
Reviewed-by: Mark Williamson
Tested-by: Mark Williamson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
