kernel/linux.git/Documentation, branch v3.18.135

mm, proc: be more verbose about unstable VMA flags in /proc//smaps

2019-01-26T08:44:29+00:00

[ Upstream commit 7550c6079846a24f30d15ac75a941c8515dbedfb ] Patch series "THP eligibility reporting via proc". This series of three patches aims at making THP eligibility reporting much more robust and long term sustainable. The trigger for the change is a regression report [2] and the long follow up discussion. In short the specific application didn't have good API to query whether a particular mapping can be backed by THP so it has used VMA flags to workaround that. These flags represent a deep internal state of VMAs and as such they should be used by userspace with a great deal of caution. A similar has happened for [3] when users complained that VM_MIXEDMAP is no longer set on DAX mappings. Again a lack of a proper API led to an abuse. The first patch in the series tries to emphasise that that the semantic of flags might change and any application consuming those should be really careful. The remaining two patches provide a more suitable interface to address [2] and provide a consistent API to query the THP status both for each VMA and process wide as well. [1] http://lkml.kernel.org/r/20181120103515.25280-1-mhocko@kernel.org [2] http://lkml.kernel.org/r/http://lkml.kernel.org/r/alpine.DEB.2.21.1809241054050.224429@chino.kir.corp.google.com [3] http://lkml.kernel.org/r/20181002100531.GC4135@quack2.suse.cz This patch (of 3): Even though vma flags exported via /proc//smaps are explicitly documented to be not guaranteed for future compatibility the warning doesn't go far enough because it doesn't mention semantic changes to those flags. And they are important as well because these flags are a deep implementation internal to the MM code and the semantic might change at any time. Let's consider two recent examples: http://lkml.kernel.org/r/20181002100531.GC4135@quack2.suse.cz : commit e1fb4a086495 "dax: remove VM_MIXEDMAP for fsdax and device dax" has : removed VM_MIXEDMAP flag from DAX VMAs. Now our testing shows that in the : mean time certain customer of ours started poking into /proc//smaps : and looks at VMA flags there and if VM_MIXEDMAP is missing among the VMA : flags, the application just fails to start complaining that DAX support is : missing in the kernel. http://lkml.kernel.org/r/alpine.DEB.2.21.1809241054050.224429@chino.kir.corp.google.com : Commit 1860033237d4 ("mm: make PR_SET_THP_DISABLE immediately active") : introduced a regression in that userspace cannot always determine the set : of vmas where thp is ineligible. : Userspace relies on the "nh" flag being emitted as part of /proc/pid/smaps : to determine if a vma is eligible to be backed by hugepages. : Previous to this commit, prctl(PR_SET_THP_DISABLE, 1) would cause thp to : be disabled and emit "nh" as a flag for the corresponding vmas as part of : /proc/pid/smaps. After the commit, thp is disabled by means of an mm : flag and "nh" is not emitted. : This causes smaps parsing libraries to assume a vma is eligible for thp : and ends up puzzling the user on why its memory is not backed by thp. In both cases userspace was relying on a semantic of a specific VMA flag. The primary reason why that happened is a lack of a proper interface. While this has been worked on and it will be fixed properly, it seems that our wording could see some refinement and be more vocal about semantic aspect of these flags as well. Link: http://lkml.kernel.org/r/20181211143641.3503-2-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Jan Kara Acked-by: Dan Williams Acked-by: David Rientjes Acked-by: Mike Rapoport Acked-by: Vlastimil Babka Cc: Dan Williams Cc: David Rientjes Cc: Paul Oppenheimer Cc: William Kucharski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

selftests: Move networking/timestamping from Documentation

2018-12-17T09:07:13+00:00

commit 3d2c86e3057995270e08693231039d9d942871f0 upstream. Remove networking from Documentation Makefile to move the test to selftests. Update networking/timestamping Makefile to work under selftests. These tests will not be run as part of selftests suite and will not be included in install targets. They can be built and run separately for now. This is part of the effort to move runnable code from Documentation. Acked-by: Jonathan Corbet Signed-off-by: Shuah Khan [ added to 3.18.y stable to remove a build warning - gregkh] Signed-off-by: Greg Kroah-Hartman

kbuild: verify that $DEPMOD is installed

2018-08-17T18:54:56+00:00

commit 934193a654c1f4d0643ddbf4b2529b508cae926e upstream. Verify that 'depmod' ($DEPMOD) is installed. This is a partial revert of commit 620c231c7a7f ("kbuild: do not check for ancient modutils tools"). Also update Documentation/process/changes.rst to refer to kmod instead of module-init-tools. Fixes kernel bugzilla #198965: https://bugzilla.kernel.org/show_bug.cgi?id=198965 Signed-off-by: Randy Dunlap Cc: Lucas De Marchi Cc: Lucas De Marchi Cc: Michal Marek Cc: Jessica Yu Cc: Chih-Wei Huang Cc: stable@vger.kernel.org # any kernel since 2012 Signed-off-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman

dm thin: fix documentation relative to low water mark threshold

2018-05-30T05:47:30+00:00

[ Upstream commit 9b28a1102efc75d81298198166ead87d643a29ce ] Fixes: 1. The use of "exceeds" when the opposite of exceeds, falls below, was meant. 2. Properly speaking, a table can not exceed a threshold. It emphasizes the important point, which is that it is the userspace daemon's responsibility to check for low free space when a device is resumed, since it won't get a special event indicating low free space in that situation. Signed-off-by: mulhern Signed-off-by: Mike Snitzer Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Documentation: pinctrl: palmas: Add ti,palmas-powerhold-override property definition

2018-04-08T09:49:48+00:00

commit 0ea66f76ba17a4b229caaadd77de694111b21769 upstream. GPIO7 is configured in POWERHOLD mode which has higher priority over DEV_ON bit and keeps the PMIC supplies on even after the DEV_ON bit is turned off. This property enables driver to over ride the POWERHOLD value to GPIO7 so as to turn off the PMIC in power off scenarios. Signed-off-by: Keerthy Acked-by: Rob Herring Signed-off-by: Linus Walleij Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

fs/proc: Stop trying to report thread stacks

2018-04-08T09:49:48+00:00

commit b18cb64ead400c01bf1580eeba330ace51f8087d upstream. This reverts more of: b76437579d13 ("procfs: mark thread stack correctly in proc//maps") ... which was partially reverted by: 65376df58217 ("proc: revert /proc//maps [stack:TID] annotation") Originally, /proc/PID/task/TID/maps was the same as /proc/TID/maps. In current kernels, /proc/PID/maps (or /proc/TID/maps even for threads) shows "[stack]" for VMAs in the mm's stack address range. In contrast, /proc/PID/task/TID/maps uses KSTK_ESP to guess the target thread's stack's VMA. This is racy, probably returns garbage and, on arches with CONFIG_TASK_INFO_IN_THREAD=y, is also crash-prone: KSTK_ESP is not safe to use on tasks that aren't known to be running ordinary process-context kernel code. This patch removes the difference and just shows "[stack]" for VMAs in the mm's stack range. This is IMO much more sensible -- the actual "stack" address really is treated specially by the VM code, and the current thread stack isn't even well-defined for programs that frequently switch stacks on their own. Reported-by: Jann Horn Signed-off-by: Andy Lutomirski Acked-by: Thomas Gleixner Cc: Al Viro Cc: Andrew Morton Cc: Borislav Petkov Cc: Brian Gerst Cc: Johannes Weiner Cc: Kees Cook Cc: Linus Torvalds Cc: Linux API Cc: Peter Zijlstra Cc: Tycho Andersen Link: http://lkml.kernel.org/r/3e678474ec14e0a0ec34c611016753eea2e1b8ba.1475257877.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

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

2018-04-08T09:49:48+00:00

commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a upstream. 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 Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

ext4: correct documentation for grpid mount option

2018-02-25T10:01:16+00:00

commit 9f0372488cc9243018a812e8cfbf27de650b187b upstream. The grpid option is currently described as being the same as nogrpid. Signed-off-by: Ernesto A. Fernández Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

arm: spear13xx: Fix dmas cells

2018-02-25T10:01:15+00:00

commit cdd10409914184c7eee5ae3e11beb890c9c16c61 upstream. The "dmas" cells for the designware DMA controller need to have only 3 properties apart from the phandle: request line, src master and destination master. But the commit 6e8887f60f60 updated it incorrectly while moving from platform code to DT. Fix it. Cc: stable@vger.kernel.org # v3.10+ Fixes: 6e8887f60f60 ("ARM: SPEAr13xx: Pass generic DW DMAC platform data from DT") Reported-by: Arnd Bergmann Signed-off-by: Viresh Kumar Signed-off-by: Olof Johansson Signed-off-by: Greg Kroah-Hartman

dt-bindings: Add vendor prefix for LEGO

2017-11-15T09:04:12+00:00

[ Upstream commit 7dcc31e2e68a386a29070384b51683ece80982bf ] Add a vendor prefix for LEGO Systems A/S Acked-by: Rob Herring Signed-off-by: David Lechner Signed-off-by: Sekhar Nori Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman