Patch series "tmpfs: inode: Reduce risk of inum overflow", v7.
In Facebook production we are seeing heavy i_ino wraparounds on tmpfs. On
affected tiers, in excess of 10% of hosts show multiple files with
different content and the same inode number, with some servers even having
as many as 150 duplicated inode numbers with differing file content.
This causes actual, tangible problems in production. For example, we have
complaints from those working on remote caches that their application is
reporting cache corruptions because it uses (device, inodenum) to
establish the identity of a particular cache object, but because it's not
unique any more, the application refuses to continue and reports cache
corruption. Even worse, sometimes applications may not even detect the
corruption but may continue anyway, causing phantom and hard to debug
behaviour.
In general, userspace applications expect that (device, inodenum) should
be enough to be uniquely point to one inode, which seems fair enough. One
might also need to check the generation, but in this case:
1. That's not currently exposed to userspace
(ioctl(...FS_IOC_GETVERSION...) returns ENOTTY on tmpfs);
2. Even with generation, there shouldn't be two live inodes with the
same inode number on one device.
In order to mitigate this, we take a two-pronged approach:
1. Moving inum generation from being global to per-sb for tmpfs. This
itself allows some reduction in i_ino churn. This works on both 64-
and 32- bit machines.
2. Adding inode{64,32} for tmpfs. This fix is supported on machines with
64-bit ino_t only: we allow users to mount tmpfs with a new inode64
option that uses the full width of ino_t, or CONFIG_TMPFS_INODE64.
You can see how this compares to previous related patches which didn't
implement this per-superblock:
- https://patchwork.kernel.org/patch/11254001/
- https://patchwork.kernel.org/patch/11023915/
This patch (of 2):
get_next_ino has a number of problems:
- It uses and returns a uint, which is susceptible to become overflowed
if a lot of volatile inodes that use get_next_ino are created.
- It's global, with no specificity per-sb or even per-filesystem. This
means it's not that difficult to cause inode number wraparounds on a
single device, which can result in having multiple distinct inodes
with the same inode number.
This patch adds a per-superblock counter that mitigates the second case.
This design also allows us to later have a specific i_ino size per-device,
for example, allowing users to choose whether to use 32- or 64-bit inodes
for each tmpfs mount. This is implemented in the next commit.
For internal shmem mounts which may be less tolerant to spinlock delays,
we implement a percpu batching scheme which only takes the stat_lock at
each batch boundary.
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/cover.1594661218.git.chris@chrisdown.name
Link: http://lkml.kernel.org/r/1986b9d63b986f08ec07a4aa4b2275e718e47d8a.1594661218.git.chris@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert the ramfs, shmem, tmpfs, devtmpfs and rootfs filesystems to the new
internal mount API as the old one will be obsoleted and removed. This
allows greater flexibility in communication of mount parameters between
userspace, the VFS and the filesystem.
See Documentation/filesystems/mount_api.txt for more information.
Note that tmpfs is slightly tricky as it can contain embedded commas, so it
can't be trivially split up using strsep() to break on commas in
generic_parse_monolithic(). Instead, tmpfs has to supply its own generic
parser.
However, if tmpfs changes, then devtmpfs and rootfs, which are wrappers
around tmpfs or ramfs, must change too - and thus so must ramfs, so these
had to be converted also.
[AV: rewritten]
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Hugh Dickins <hughd@google.com>
cc: linux-mm@kvack.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The igrab() in shmem_unuse() looks good, but we forgot that it gives no
protection against concurrent unmounting: a point made by Konstantin
Khlebnikov eight years ago, and then fixed in 2.6.39 by 778dd893ae
("tmpfs: fix race between umount and swapoff"). The current 5.1-rc
swapoff is liable to hit "VFS: Busy inodes after unmount of tmpfs.
Self-destruct in 5 seconds. Have a nice day..." followed by GPF.
Once again, give up on using igrab(); but don't go back to making such
heavy-handed use of shmem_swaplist_mutex as last time: that would spoil
the new design, and I expect could deadlock inside shmem_swapin_page().
Instead, shmem_unuse() just raise a "stop_eviction" count in the shmem-
specific inode, and shmem_evict_inode() wait for that to go down to 0.
Call it "stop_eviction" rather than "swapoff_busy" because it can be put
to use for others later (huge tmpfs patches expect to use it).
That simplifies shmem_unuse(), protecting it from both unlink and
unmount; and in practice lets it locate all the swap in its first try.
But do not rely on that: there's still a theoretical case, when
shmem_writepage() might have been preempted after its get_swap_page(),
before making the swap entry visible to swapoff.
[hughd@google.com: remove incorrect list_del()]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1904091133570.1898@eggly.anvils
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1904081259400.1523@eggly.anvils
Fixes: b56a2d8af9 ("mm: rid swapoff of quadratic complexity")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Kelley Nielsen <kelleynnn@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vineeth Pillai <vpillai@digitalocean.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch was initially posted by Kelley Nielsen. Reposting the patch
with all review comments addressed and with minor modifications and
optimizations. Also, folding in the fixes offered by Hugh Dickins and
Huang Ying. Tests were rerun and commit message updated with new
results.
try_to_unuse() is of quadratic complexity, with a lot of wasted effort.
It unuses swap entries one by one, potentially iterating over all the
page tables for all the processes in the system for each one.
This new proposed implementation of try_to_unuse simplifies its
complexity to linear. It iterates over the system's mms once, unusing
all the affected entries as it walks each set of page tables. It also
makes similar changes to shmem_unuse.
Improvement
swapoff was called on a swap partition containing about 6G of data, in a
VM(8cpu, 16G RAM), and calls to unuse_pte_range() were counted.
Present implementation....about 1200M calls(8min, avg 80% cpu util).
Prototype.................about 9.0K calls(3min, avg 5% cpu util).
Details
In shmem_unuse(), iterate over the shmem_swaplist and, for each
shmem_inode_info that contains a swap entry, pass it to
shmem_unuse_inode(), along with the swap type. In shmem_unuse_inode(),
iterate over its associated xarray, and store the index and value of
each swap entry in an array for passing to shmem_swapin_page() outside
of the RCU critical section.
In try_to_unuse(), instead of iterating over the entries in the type and
unusing them one by one, perhaps walking all the page tables for all the
processes for each one, iterate over the mmlist, making one pass. Pass
each mm to unuse_mm() to begin its page table walk, and during the walk,
unuse all the ptes that have backing store in the swap type received by
try_to_unuse(). After the walk, check the type for orphaned swap
entries with find_next_to_unuse(), and remove them from the swap cache.
If find_next_to_unuse() starts over at the beginning of the type, repeat
the check of the shmem_swaplist and the walk a maximum of three times.
Change unuse_mm() and the intervening walk functions down to
unuse_pte_range() to take the type as a parameter, and to iterate over
their entire range, calling the next function down on every iteration.
In unuse_pte_range(), make a swap entry from each pte in the range using
the passed in type. If it has backing store in the type, call
swapin_readahead() to retrieve the page and pass it to unuse_pte().
Pass the count of pages_to_unuse down the page table walks in
try_to_unuse(), and return from the walk when the desired number of
pages has been swapped back in.
Link: http://lkml.kernel.org/r/20190114153129.4852-2-vpillai@digitalocean.com
Signed-off-by: Vineeth Remanan Pillai <vpillai@digitalocean.com>
Signed-off-by: Kelley Nielsen <kelleynnn@gmail.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the addition of memfd hugetlbfs support, we now have the situation
where memfd depends on TMPFS -or- HUGETLBFS. Previously, memfd was only
supported on tmpfs, so it made sense that the code resided in shmem.c.
In the current code, memfd is only functional if TMPFS is defined. If
HUGETLFS is defined and TMPFS is not defined, then memfd functionality
will not be available for hugetlbfs. This does not cause BUGs, just a
lack of potentially desired functionality.
Code is restructured in the following way:
- include/linux/memfd.h is a new file containing memfd specific
definitions previously contained in shmem_fs.h.
- mm/memfd.c is a new file containing memfd specific code previously
contained in shmem.c.
- memfd specific code is removed from shmem_fs.h and shmem.c.
- A new config option MEMFD_CREATE is added that is defined if TMPFS
or HUGETLBFS is defined.
No functional changes are made to the code: restructuring only.
Link: http://lkml.kernel.org/r/20180415182119.4517-4-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Marc-Andr Lureau <marcandre.lureau@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull drm updates from Dave Airlie:
"This is the main drm pull request for v4.15.
Core:
- Atomic object lifetime fixes
- Atomic iterator improvements
- Sparse/smatch fixes
- Legacy kms ioctls to be interruptible
- EDID override improvements
- fb/gem helper cleanups
- Simple outreachy patches
- Documentation improvements
- Fix dma-buf rcu races
- DRM mode object leasing for improving VR use cases.
- vgaarb improvements for non-x86 platforms.
New driver:
- tve200: Faraday Technology TVE200 block.
This "TV Encoder" encodes a ITU-T BT.656 stream and can be found in
the StorLink SL3516 (later Cortina Systems CS3516) as well as the
Grain Media GM8180.
New bridges:
- SiI9234 support
New panels:
- S6E63J0X03, OTM8009A, Seiko 43WVF1G, 7" rpi touch panel, Toshiba
LT089AC19000, Innolux AT043TN24
i915:
- Remove Coffeelake from alpha support
- Cannonlake workarounds
- Infoframe refactoring for DisplayPort
- VBT updates
- DisplayPort vswing/emph/buffer translation refactoring
- CCS fixes
- Restore GPU clock boost on missed vblanks
- Scatter list updates for userptr allocations
- Gen9+ transition watermarks
- Display IPC (Isochronous Priority Control)
- Private PAT management
- GVT: improved error handling and pci config sanitizing
- Execlist refactoring
- Transparent Huge Page support
- User defined priorities support
- HuC/GuC firmware refactoring
- DP MST fixes
- eDP power sequencing fixes
- Use RCU instead of stop_machine
- PSR state tracking support
- Eviction fixes
- BDW DP aux channel timeout fixes
- LSPCON fixes
- Cannonlake PLL fixes
amdgpu:
- Per VM BO support
- Powerplay cleanups
- CI powerplay support
- PASID mgr for kfd
- SR-IOV fixes
- initial GPU reset for vega10
- Prime mmap support
- TTM updates
- Clock query interface for Raven
- Fence to handle ioctl
- UVD encode ring support on Polaris
- Transparent huge page DMA support
- Compute LRU pipe tweaks
- BO flag to allow buffers to opt out of implicit sync
- CTX priority setting API
- VRAM lost infrastructure plumbing
qxl:
- fix flicker since atomic rework
amdkfd:
- Further improvements from internal AMD tree
- Usermode events
- Drop radeon support
nouveau:
- Pascal temperature sensor support
- Improved BAR2 handling
- MMU rework to support Pascal MMU
exynos:
- Improved HDMI/mixer support
- HDMI audio interface support
tegra:
- Prep work for tegra186
- Cleanup/fixes
msm:
- Preemption support for a5xx
- Display fixes for 8x96 (snapdragon 820)
- Async cursor plane fixes
- FW loading rework
- GPU debugging improvements
vc4:
- Prep for DSI panels
- fix T-format tiling scanout
- New madvise ioctl
Rockchip:
- LVDS support
omapdrm:
- omap4 HDMI CEC support
etnaviv:
- GPU performance counters groundwork
sun4i:
- refactor driver load + TCON backend
- HDMI improvements
- A31 support
- Misc fixes
udl:
- Probe/EDID read fixes.
tilcdc:
- Misc fixes.
pl111:
- Support more variants
adv7511:
- Improve EDID handling.
- HDMI CEC support
sii8620:
- Add remote control support"
* tag 'drm-for-v4.15' of git://people.freedesktop.org/~airlied/linux: (1480 commits)
drm/rockchip: analogix_dp: Use mutex rather than spinlock
drm/mode_object: fix documentation for object lookups.
drm/i915: Reorder context-close to avoid calling i915_vma_close() under RCU
drm/i915: Move init_clock_gating() back to where it was
drm/i915: Prune the reservation shared fence array
drm/i915: Idle the GPU before shinking everything
drm/i915: Lock llist_del_first() vs llist_del_all()
drm/i915: Calculate ironlake intermediate watermarks correctly, v2.
drm/i915: Disable lazy PPGTT page table optimization for vGPU
drm/i915/execlists: Remove the priority "optimisation"
drm/i915: Filter out spurious execlists context-switch interrupts
drm/amdgpu: use irq-safe lock for kiq->ring_lock
drm/amdgpu: bypass lru touch for KIQ ring submission
drm/amdgpu: Potential uninitialized variable in amdgpu_vm_update_directories()
drm/amdgpu: potential uninitialized variable in amdgpu_vce_ring_parse_cs()
drm/amd/powerplay: initialize a variable before using it
drm/amd/powerplay: suppress KASAN out of bounds warning in vega10_populate_all_memory_levels
drm/amd/amdgpu: fix evicted VRAM bo adjudgement condition
drm/vblank: Tune drm_crtc_accurate_vblank_count() WARN down to a debug
drm/rockchip: add CONFIG_OF dependency for lvds
...
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Even if user asked to allocate huge pages always (huge=always), we
should be able to free up some memory by splitting pages which are
partly byound i_size if memory presure comes or once we hit limit on
filesystem size (-o size=).
In order to do this we maintain per-superblock list of inodes, which
potentially have huge pages on the border of file size.
Per-fs shrinker can reclaim memory by splitting such pages.
If we hit -ENOSPC during shmem_getpage_gfp(), we try to split a page to
free up space on the filesystem and retry allocation if it succeed.
Link: http://lkml.kernel.org/r/1466021202-61880-37-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch extends khugepaged to support collapse of tmpfs/shmem pages.
We share fair amount of infrastructure with anon-THP collapse.
Few design points:
- First we are looking for VMA which can be suitable for mapping huge
page;
- If the VMA maps shmem file, the rest scan/collapse operations
operates on page cache, not on page tables as in anon VMA case.
- khugepaged_scan_shmem() finds a range which is suitable for huge
page. The scan is lockless and shouldn't disturb system too much.
- once the candidate for collapse is found, collapse_shmem() attempts
to create a huge page:
+ scan over radix tree, making the range point to new huge page;
+ new huge page is not-uptodate, locked and freezed (refcount
is 0), so nobody can touch them until we say so.
+ we swap in pages during the scan. khugepaged_scan_shmem()
filters out ranges with more than khugepaged_max_ptes_swap
swapped out pages. It's HPAGE_PMD_NR/8 by default.
+ old pages are isolated, unmapped and put to local list in case
to be restored back if collapse failed.
- if collapse succeed, we retract pte page tables from VMAs where huge
pages mapping is possible. The huge page will be mapped as PMD on
next minor fault into the range.
Link: http://lkml.kernel.org/r/1466021202-61880-35-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here's basic implementation of huge pages support for shmem/tmpfs.
It's all pretty streight-forward:
- shmem_getpage() allcoates huge page if it can and try to inserd into
radix tree with shmem_add_to_page_cache();
- shmem_add_to_page_cache() puts the page onto radix-tree if there's
space for it;
- shmem_undo_range() removes huge pages, if it fully within range.
Partial truncate of huge pages zero out this part of THP.
This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE)
behaviour. As we don't really create hole in this case,
lseek(SEEK_HOLE) may have inconsistent results depending what
pages happened to be allocated.
- no need to change shmem_fault: core-mm will map an compound page as
huge if VMA is suitable;
Link: http://lkml.kernel.org/r/1466021202-61880-30-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide a shmem_get_unmapped_area method in file_operations, called at
mmap time to decide the mapping address. It could be conditional on
CONFIG_TRANSPARENT_HUGEPAGE, but save #ifdefs in other places by making
it unconditional.
shmem_get_unmapped_area() first calls the usual mm->get_unmapped_area
(which we treat as a black box, highly dependent on architecture and
config and executable layout). Lots of conditions, and in most cases it
just goes with the address that chose; but when our huge stars are
rightly aligned, yet that did not provide a suitable address, go back to
ask for a larger arena, within which to align the mapping suitably.
There have to be some direct calls to shmem_get_unmapped_area(), not via
the file_operations: because of the way shmem_zero_setup() is called to
create a shmem object late in the mmap sequence, when MAP_SHARED is
requested with MAP_ANONYMOUS or /dev/zero. Though this only matters
when /proc/sys/vm/shmem_huge has been set.
Link: http://lkml.kernel.org/r/1466021202-61880-29-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds new mount option "huge=". It can have following values:
- "always":
Attempt to allocate huge pages every time we need a new page;
- "never":
Do not allocate huge pages;
- "within_size":
Only allocate huge page if it will be fully within i_size.
Also respect fadvise()/madvise() hints;
- "advise:
Only allocate huge pages if requested with fadvise()/madvise();
Default is "never" for now.
"mount -o remount,huge= /mountpoint" works fine after mount: remounting
huge=never will not attempt to break up huge pages at all, just stop
more from being allocated.
No new config option: put this under CONFIG_TRANSPARENT_HUGEPAGE, which
is the appropriate option to protect those who don't want the new bloat,
and with which we shall share some pmd code.
Prohibit the option when !CONFIG_TRANSPARENT_HUGEPAGE, just as mpol is
invalid without CONFIG_NUMA (was hidden in mpol_parse_str(): make it
explicit).
Allow enabling THP only if the machine has_transparent_hugepage().
But what about Shmem with no user-visible mount? SysV SHM, memfds,
shared anonymous mmaps (of /dev/zero or MAP_ANONYMOUS), GPU drivers' DRM
objects, Ashmem. Though unlikely to suit all usages, provide sysfs knob
/sys/kernel/mm/transparent_hugepage/shmem_enabled to experiment with
huge on those.
And allow shmem_enabled two further values:
- "deny":
For use in emergencies, to force the huge option off from
all mounts;
- "force":
Force the huge option on for all - very useful for testing;
Based on patch by Hugh Dickins.
Link: http://lkml.kernel.org/r/1466021202-61880-28-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Following the previous patch, further reduction of /proc/pid/smaps cost
is possible for private writable shmem mappings with unpopulated areas
where the page walk invokes the .pte_hole function. We can use radix
tree iterator for each such area instead of calling find_get_entry() in
a loop. This is possible at the extra maintenance cost of introducing
another shmem function shmem_partial_swap_usage().
To demonstrate the diference, I have measured this on a process that
creates a private writable 2GB mapping of a partially swapped out
/dev/shm/file (which cannot employ the optimizations from the prvious
patch) and doesn't populate it at all. I time how long does it take to
cat /proc/pid/smaps of this process 100 times.
Before this patch:
real 0m3.831s
user 0m0.180s
sys 0m3.212s
After this patch:
real 0m1.176s
user 0m0.180s
sys 0m0.684s
The time is similar to the case where a radix tree iterator is employed
on the whole mapping.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
