linux/Documentation/filesystems, branch v4.5

efi: Make efivarfs entries immutable by default

2016-02-10T16:25:52Z

"rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by: Peter Jones Tested-by: Lee, Chun-Yi Acked-by: Matthew Garrett Signed-off-by: Matt Fleming

mm: polish virtual memory accounting

2016-02-03T16:28:43Z

* add VM_STACK as alias for VM_GROWSUP/DOWN depending on architecture * always account VMAs with flag VM_STACK as stack (as it was before) * cleanup classifying helpers * update comments and documentation Signed-off-by: Konstantin Khlebnikov Tested-by: Sudip Mukherjee Cc: Cyrill Gorcunov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: revert /proc//maps [stack:TID] annotation

2016-02-03T16:28:43Z

Commit b76437579d13 ("procfs: mark thread stack correctly in proc//maps") added [stack:TID] annotation to /proc//maps. Finding the task of a stack VMA requires walking the entire thread list, turning this into quadratic behavior: a thousand threads means a thousand stacks, so the rendering of /proc//maps needs to look at a million combinations. The cost is not in proportion to the usefulness as described in the patch. Drop the [stack:TID] annotation to make /proc//maps (and /proc//numa_maps) usable again for higher thread counts. The [stack] annotation inside /proc//task//maps is retained, as identifying the stack VMA there is an O(1) operation. Siddesh said: "The end users needed a way to identify thread stacks programmatically and there wasn't a way to do that. I'm afraid I no longer remember (or have access to the resources that would aid my memory since I changed employers) the details of their requirement. However, I did do this on my own time because I thought it was an interesting project for me and nobody really gave any feedback then as to its utility, so as far as I am concerned you could roll back the main thread maps information since the information is available in the thread-specific files" Signed-off-by: Johannes Weiner Cc: "Kirill A. Shutemov" Cc: Siddhesh Poyarekar Cc: Shaohua Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Documentation/filesystems/vfat.txt: update the limitation for fat fallocate

2016-01-21T01:09:18Z

Update the limitation for fat fallocate. Signed-off-by: Namjae Jeon Signed-off-by: Amit Sahrawat Cc: OGAWA Hirofumi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'docs-4.5' of git://git.lwn.net/linux

2016-01-17T19:55:07Z

Pull documentation updates from Jon Corbet: "A relatively boring cycle in the docs tree. There's a few kernel-doc fixes and various document tweaks. One patch reaches out of the documentation subtree to fix a comment in init/do_mounts_rd.c. There didn't seem to be anybody more appropriate to take that one, so I accepted it" * tag 'docs-4.5' of git://git.lwn.net/linux: (29 commits) thermal: add description for integral_cutoff unit Documentation: update libhugetlbfs site url Documentation: Explain pci=conf1,conf2 more verbosely DMA-API: fix confusing sentence in Documentation/DMA-API.txt Documentation: translations: update linux cross reference link Documentation: fix typo in CodingStyle init, Documentation: Remove ramdisk_blocksize mentions Documentation-getdelays: Apply a recommendation from "checkpatch.pl" in main() Documentation: HOWTO: update versions from 3.x to 4.x Documentation: remove outdated references from translations Doc: treewide: Fix grammar "a" to "an" Documentation: cpu-hotplug: Fix sysfs mount instructions can-doc: Add hint about getting timestamps Fix CFQ I/O scheduler parameter name in documentation Documentation: arm: remove dead links from Marvell Berlin docs Documentation: HOWTO: update code cross reference link Doc: Docbook/iio: Fix typo in iio.tmpl DocBook: make index.html generation less verbose by default DocBook: Cleanup: remove an unused $(call) line DocBook: Add a help message for DOCBOOKS env var ...

Merge branch 'akpm' (patches from Andrew)

2016-01-15T19:41:44Z

Merge first patch-bomb from Andrew Morton: - A few hotfixes which missed 4.4 becasue I was asleep. cc'ed to -stable - A few misc fixes - OCFS2 updates - Part of MM. Including pretty large changes to page-flags handling and to thp management which have been buffered up for 2-3 cycles now. I have a lot of MM material this time. [ It turns out the THP part wasn't quite ready, so that got dropped from this series - Linus ] * emailed patches from Andrew Morton : (117 commits) zsmalloc: reorganize struct size_class to pack 4 bytes hole mm/zbud.c: use list_last_entry() instead of list_tail_entry() zram/zcomp: do not zero out zcomp private pages zram: pass gfp from zcomp frontend to backend zram: try vmalloc() after kmalloc() zram/zcomp: use GFP_NOIO to allocate streams mm: add tracepoint for scanning pages drivers/base/memory.c: fix kernel warning during memory hotplug on ppc64 mm/page_isolation: use macro to judge the alignment mm: fix noisy sparse warning in LIBCFS_ALLOC_PRE() mm: rework virtual memory accounting include/linux/memblock.h: fix ordering of 'flags' argument in comments mm: move lru_to_page to mm_inline.h Documentation/filesystems: describe the shared memory usage/accounting memory-hotplug: don't BUG() in register_memory_resource() hugetlb: make mm and fs code explicitly non-modular mm/swapfile.c: use list_for_each_entry_safe in free_swap_count_continuations mm: /proc/pid/clear_refs: no need to clear VM_SOFTDIRTY in clear_soft_dirty_pmd() mm: make sure isolate_lru_page() is never called for tail page vmstat: make vmstat_updater deferrable again and shut down on idle ...

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-01-15T00:03:57Z

Pull vfs fix from Al Viro: "Don't put symlink bodies in pagecache into highmem" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: Make sure that highmem pages are not added to symlink page cache

Documentation/filesystems: describe the shared memory usage/accounting

2016-01-15T00:00:49Z

The Shared Memory accounting support is present in Kernel since commit 4b02108ac1b3 ("mm: oom analysis: add shmem vmstat") and in userland free(1) since 2014. This patch updates the Documentation to reflect this change. Signed-off-by: Rodrigo Freire Acked-by: Vlastimil Babka Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status

2016-01-15T00:00:49Z

There are several shortcomings with the accounting of shared memory (SysV shm, shared anonymous mapping, mapping of a tmpfs file). The values in /proc//status and <...>/statm don't allow to distinguish between shmem memory and a shared mapping to a regular file, even though theirs implication on memory usage are quite different: during reclaim, file mapping can be dropped or written back on disk, while shmem needs a place in swap. Also, to distinguish the memory occupied by anonymous and file mappings, one has to read the /proc/pid/statm file, which has a field for the file mappings (again, including shmem) and total memory occupied by these mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting the value for anonymous mappings only is thus not exactly user-friendly (the statm file is intended to be rather efficiently machine-readable). To address both of these shortcomings, this patch adds a breakdown of VmRSS in /proc//status via new fields RssAnon, RssFile and RssShmem, making use of the previous preparatory patch. These fields tell the user the memory occupied by private anonymous pages, mapped regular files and shmem, respectively. Other existing fields in /status and /statm files are left without change. The /statm file can be extended in the future, if there's a need for that. Example (part of) /proc/pid/status output including the new Rss* fields: VmPeak: 2001008 kB VmSize: 2001004 kB VmLck: 0 kB VmPin: 0 kB VmHWM: 5108 kB VmRSS: 5108 kB RssAnon: 92 kB RssFile: 1324 kB RssShmem: 3692 kB VmData: 192 kB VmStk: 136 kB VmExe: 4 kB VmLib: 1784 kB VmPTE: 3928 kB VmPMD: 20 kB VmSwap: 0 kB HugetlbPages: 0 kB [vbabka@suse.cz: forward-porting, tweak changelog] Signed-off-by: Jerome Marchand Signed-off-by: Vlastimil Babka Acked-by: Konstantin Khlebnikov Acked-by: Michal Hocko Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, proc: account for shmem swap in /proc/pid/smaps

2016-01-15T00:00:49Z

Currently, /proc/pid/smaps will always show "Swap: 0 kB" for shmem-backed mappings, even if the mapped portion does contain pages that were swapped out. This is because unlike private anonymous mappings, shmem does not change pte to swap entry, but pte_none when swapping the page out. In the smaps page walk, such page thus looks like it was never faulted in. This patch changes smaps_pte_entry() to determine the swap status for such pte_none entries for shmem mappings, similarly to how mincore_page() does it. Swapped out shmem pages are thus accounted for. For private mappings of tmpfs files that COWed some of the pages, swaped out status of the original shmem pages is naturally ignored. If some of the private copies was also swapped out, they are accounted via their page table swap entries, so the resulting reported swap usage is then a sum of both swapped out private copies, and swapped out shmem pages that were not COWed. No double accounting can thus happen. The accounting is arguably still not as precise as for private anonymous mappings, since now we will count also pages that the process in question never accessed, but another process populated them and then let them become swapped out. I believe it is still less confusing and subtle than not showing any swap usage by shmem mappings at all. Swapped out counter might of interest of users who would like to prevent from future swapins during performance critical operation and pre-fault them at their convenience. Especially for larger swapped out regions the cost of swapin is much higher than a fresh page allocation. So a differentiation between pte_none vs. swapped out is important for those usecases. One downside of this patch is that it makes /proc/pid/smaps more expensive for shmem mappings, as we consult the radix tree for each pte_none entry, so the overal complexity is O(n*log(n)). I have measured this on a process that creates a 2GB mapping and dirties single pages with a stride of 2MB, and time how long does it take to cat /proc/pid/smaps of this process 100 times. Private anonymous mapping: real 0m0.949s user 0m0.116s sys 0m0.348s Mapping of a /dev/shm/file: real 0m3.831s user 0m0.180s sys 0m3.212s The difference is rather substantial, so the next patch will reduce the cost for shared or read-only mappings. In a less controlled experiment, I've gathered pids of processes on my desktop that have either '/dev/shm/*' or 'SYSV*' in smaps. This included the Chrome browser and some KDE processes. Again, I've run cat /proc/pid/smaps on each 100 times. Before this patch: real 0m9.050s user 0m0.518s sys 0m8.066s After this patch: real 0m9.221s user 0m0.541s sys 0m8.187s This suggests low impact on average systems. Note that this patch doesn't attempt to adjust the SwapPss field for shmem mappings, which would need extra work to determine who else could have the pages mapped. Thus the value stays zero except for COWed swapped out pages in a shmem mapping, which are accounted as usual. Signed-off-by: Vlastimil Babka Acked-by: Konstantin Khlebnikov Acked-by: Jerome Marchand Acked-by: Michal Hocko Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds