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2020-08-13Merge tag 'docs-5.9-2' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation fixes from Jonathan Corbet: "A handful of obvious fixes that wandered in during the merge window" * tag 'docs-5.9-2' of git://git.lwn.net/linux: Documentation/locking/locktypes: fix the typo doc/zh_CN: resolve undefined label warning in admin-guide index doc/zh_CN: fix title heading markup in admin-guide cpu-load docs: remove the 2.6 "Upgrading I2C Drivers" guide docs: Correct the release date of 5.2 stable mailmap: Update comments for with format and more detalis docs: cdrom: Fix a typo and rst markup Doc: admin-guide: use correct legends in kernel-parameters.txt Documentation/features: refresh RISC-V arch support files documentation: coccinelle: Improve command example for make C={1,2} Core-api: Documentation: Replace deprecated :c:func: Usage Dev-tools: Documentation: Replace deprecated :c:func: Usage Filesystems: Documentation: Replace deprecated :c:func: Usage docs: trace: fix a typo
2020-08-11Core-api: Documentation: Replace deprecated :c:func: UsagePuranjay Mohan
Replace :c:func: with func() as the previous usage is deprecated. Signed-off-by: Puranjay Mohan <puranjay12@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Link: https://lore.kernel.org/r/20200810183019.22170-1-puranjay12@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-08-07Merge tag 'powerpc-5.9-1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc updates from Michael Ellerman: - Add support for (optionally) using queued spinlocks & rwlocks. - Support for a new faster system call ABI using the scv instruction on Power9 or later. - Drop support for the PROT_SAO mmap/mprotect flag as it will be unsupported on Power10 and future processors, leaving us with no way to implement the functionality it requests. This risks breaking userspace, though we believe it is unused in practice. - A bug fix for, and then the removal of, our custom stack expansion checking. We now allow stack expansion up to the rlimit, like other architectures. - Remove the remnants of our (previously disabled) topology update code, which tried to react to NUMA layout changes on virtualised systems, but was prone to crashes and other problems. - Add PMU support for Power10 CPUs. - A change to our signal trampoline so that we don't unbalance the link stack (branch return predictor) in the signal delivery path. - Lots of other cleanups, refactorings, smaller features and so on as usual. Thanks to: Abhishek Goel, Alastair D'Silva, Alexander A. Klimov, Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann, Athira Rajeev, Balamuruhan S, Bharata B Rao, Bill Wendling, Bin Meng, Cédric Le Goater, Chris Packham, Christophe Leroy, Christoph Hellwig, Daniel Axtens, Dan Williams, David Lamparter, Desnes A. Nunes do Rosario, Erhard F., Finn Thain, Frederic Barrat, Ganesh Goudar, Gautham R. Shenoy, Geoff Levand, Greg Kurz, Gustavo A. R. Silva, Hari Bathini, Harish, Imre Kaloz, Joel Stanley, Joe Perches, John Crispin, Jordan Niethe, Kajol Jain, Kamalesh Babulal, Kees Cook, Laurent Dufour, Leonardo Bras, Li RongQing, Madhavan Srinivasan, Mahesh Salgaonkar, Mark Cave-Ayland, Michal Suchanek, Milton Miller, Mimi Zohar, Murilo Opsfelder Araujo, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nayna Jain, Nicholas Piggin, Oliver O'Halloran, Palmer Dabbelt, Pedro Miraglia Franco de Carvalho, Philippe Bergheaud, Pingfan Liu, Pratik Rajesh Sampat, Qian Cai, Qinglang Miao, Randy Dunlap, Ravi Bangoria, Sachin Sant, Sam Bobroff, Sandipan Das, Santosh Sivaraj, Satheesh Rajendran, Shirisha Ganta, Sourabh Jain, Srikar Dronamraju, Stan Johnson, Stephen Rothwell, Thadeu Lima de Souza Cascardo, Thiago Jung Bauermann, Tom Lane, Vaibhav Jain, Vladis Dronov, Wei Yongjun, Wen Xiong, YueHaibing. * tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (337 commits) selftests/powerpc: Fix pkey syscall redefinitions powerpc: Fix circular dependency between percpu.h and mmu.h powerpc/powernv/sriov: Fix use of uninitialised variable selftests/powerpc: Skip vmx/vsx/tar/etc tests on older CPUs powerpc/40x: Fix assembler warning about r0 powerpc/papr_scm: Add support for fetching nvdimm 'fuel-gauge' metric powerpc/papr_scm: Fetch nvdimm performance stats from PHYP cpuidle: pseries: Fixup exit latency for CEDE(0) cpuidle: pseries: Add function to parse extended CEDE records cpuidle: pseries: Set the latency-hint before entering CEDE selftests/powerpc: Fix online CPU selection powerpc/perf: Consolidate perf_callchain_user_[64|32]() powerpc/pseries/hotplug-cpu: Remove double free in error path powerpc/pseries/mobility: Add pr_debug() for device tree changes powerpc/pseries/mobility: Set pr_fmt() powerpc/cacheinfo: Warn if cache object chain becomes unordered powerpc/cacheinfo: Improve diagnostics about malformed cache lists powerpc/cacheinfo: Use name@unit instead of full DT path in debug messages powerpc/cacheinfo: Set pr_fmt() powerpc: fix function annotations to avoid section mismatch warnings with gcc-10 ...
2020-08-04Merge tag 'docs-5.9' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation updates from Jonathan Corbet: "It's been a busy cycle for documentation - hopefully the busiest for a while to come. Changes include: - Some new Chinese translations - Progress on the battle against double words words and non-HTTPS URLs - Some block-mq documentation - More RST conversions from Mauro. At this point, that task is essentially complete, so we shouldn't see this kind of churn again for a while. Unless we decide to switch to asciidoc or something...:) - Lots of typo fixes, warning fixes, and more" * tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits) scripts/kernel-doc: optionally treat warnings as errors docs: ia64: correct typo mailmap: add entry for <alobakin@marvell.com> doc/zh_CN: add cpu-load Chinese version Documentation/admin-guide: tainted-kernels: fix spelling mistake MAINTAINERS: adjust kprobes.rst entry to new location devices.txt: document rfkill allocation PCI: correct flag name docs: filesystems: vfs: correct flag name docs: filesystems: vfs: correct sync_mode flag names docs: path-lookup: markup fixes for emphasis docs: path-lookup: more markup fixes docs: path-lookup: fix HTML entity mojibake CREDITS: Replace HTTP links with HTTPS ones docs: process: Add an example for creating a fixes tag doc/zh_CN: add Chinese translation prefer section doc/zh_CN: add clearing-warn-once Chinese version doc/zh_CN: add admin-guide index doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label futex: MAINTAINERS: Re-add selftests directory ...
2020-08-04Merge tag 'printk-for-5.9' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Herbert Xu made printk header file self-contained. - Andy Shevchenko and Sergey Senozhatsky cleaned up console->setup() error handling. - Andy Shevchenko did some cleanups (e.g. sparse warning) in vsprintf code. - Minor documentation updates. * tag 'printk-for-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: lib/vsprintf: Force type of flags value for gfp_t lib/vsprintf: Replace custom spec to print decimals with generic one lib/vsprintf: Replace hidden BUILD_BUG_ON() with static_assert() printk: Make linux/printk.h self-contained doc:kmsg: explicitly state the return value in case of SEEK_CUR Replace HTTP links with HTTPS ones: vsprintf hvc: unify console setup naming console: Fix trivia typo 'change' -> 'chance' console: Propagate error code from console ->setup() tty: hvc: Return proper error code from console ->setup() hook serial: sunzilog: Return proper error code from console ->setup() hook serial: sunsab: Return proper error code from console ->setup() hook mips: Return proper error code from console ->setup() hook
2020-08-03Merge branch 'linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 Pull crypto updates from Herbert Xu: "API: - Add support for allocating transforms on a specific NUMA Node - Introduce the flag CRYPTO_ALG_ALLOCATES_MEMORY for storage users Algorithms: - Drop PMULL based ghash on arm64 - Fixes for building with clang on x86 - Add sha256 helper that does the digest in one go - Add SP800-56A rev 3 validation checks to dh Drivers: - Permit users to specify NUMA node in hisilicon/zip - Add support for i.MX6 in imx-rngc - Add sa2ul crypto driver - Add BA431 hwrng driver - Add Ingenic JZ4780 and X1000 hwrng driver - Spread IRQ affinity in inside-secure and marvell/cesa" * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (157 commits) crypto: sa2ul - Fix inconsistent IS_ERR and PTR_ERR hwrng: core - remove redundant initialization of variable ret crypto: x86/curve25519 - Remove unused carry variables crypto: ingenic - Add hardware RNG for Ingenic JZ4780 and X1000 dt-bindings: RNG: Add Ingenic RNG bindings. crypto: caam/qi2 - add module alias crypto: caam - add more RNG hw error codes crypto: caam/jr - remove incorrect reference to caam_jr_register() crypto: caam - silence .setkey in case of bad key length crypto: caam/qi2 - create ahash shared descriptors only once crypto: caam/qi2 - fix error reporting for caam_hash_alloc crypto: caam - remove deadcode on 32-bit platforms crypto: ccp - use generic power management crypto: xts - Replace memcpy() invocation with simple assignment crypto: marvell/cesa - irq balance crypto: inside-secure - irq balance crypto: ecc - SP800-56A rev 3 local public key validation crypto: dh - SP800-56A rev 3 local public key validation crypto: dh - check validity of Z before export lib/mpi: Add mpi_sub_ui() ...
2020-07-23docs: core-api/printk-formats.rst: use literal block syntaxDaniel W. S. Almeida
Fix the following warning: WARNING: Definition list ends without a blank line; unexpected unindent. By switching to the literal block syntax. Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com> Link: https://lore.kernel.org/r/20200718165107.625847-8-dwlsalmeida@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-23docs/core-api: memory-allocation: describe reclaim behaviourMike Rapoport
Changelog of commit dcda9b04713c ("mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic") has very nice description of GFP flags that affect reclaim behaviour of the page allocator. It would be pity to keep this description buried in the log so let's expose it in the Documentation/ as well. Cc: Michal Hocko <mhocko@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Link: https://lore.kernel.org/r/20200719153641.231131-1-rppt@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-23Documentation: fix typo for core-api/cpu_hotplug documentationYaohui Wang
fix typo for core-api/cpu_hotplug documentation Signed-off-by: Yaohui Wang <dillionmango@gmail.com> Link: https://lore.kernel.org/r/20200722073818.20605-1-dillionmango@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-23padata: fold padata_alloc_possible() into padata_alloc()Daniel Jordan
There's no reason to have two interfaces when there's only one caller. Removing _possible saves text and simplifies future changes. Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-07-23padata: remove stop functionDaniel Jordan
padata_stop() has two callers and is unnecessary in both cases. When pcrypt calls it before padata_free(), it's being unloaded so there are no outstanding padata jobs[0]. When __padata_free() calls it, it's either along the same path or else pcrypt initialization failed, which of course means there are also no outstanding jobs. Removing it simplifies padata and saves text. [0] https://lore.kernel.org/linux-crypto/20191119225017.mjrak2fwa5vccazl@gondor.apana.org.au/ Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-07-16powerpc/pseries: remove cede offline state for CPUsNathan Lynch
This effectively reverts commit 3aa565f53c39 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state"), which added an offline mode for CPUs which uses the H_CEDE hcall instead of the architected stop-self RTAS function in order to facilitate "folding" of dedicated mode processors on PowerVM platforms to achieve energy savings. This has been the default offline mode since its introduction. There's nothing about stop-self that would prevent the hypervisor from achieving the energy savings available via H_CEDE, so the original premise of this change appears to be flawed. I also have encountered the claim that the transition to and from ceded state is much faster than stop-self/start-cpu. Certainly we would not want to use stop-self as an *idle* mode. That is what H_CEDE is for. However, this difference is insignificant in the context of Linux CPU hotplug, where the latency of an offline or online operation on current systems is on the order of 100ms, mainly attributable to all the various subsystems' cpuhp callbacks. The cede offline mode also prevents accurate accounting, as discussed before: https://lore.kernel.org/linuxppc-dev/1571740391-3251-1-git-send-email-ego@linux.vnet.ibm.com/ Unconditionally use stop-self to offline processor threads. This is the architected method for offlining CPUs on PAPR systems. The "cede_offline" boot parameter is rendered obsolete. Removing this code enables the removal of the partition suspend code which temporarily onlines all present CPUs. Fixes: 3aa565f53c39 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state") Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200612051238.1007764-2-nathanl@linux.ibm.com
2020-07-13Documentation: printk-basics: eliminate duplicated wordRandy Dunlap
Drop the doubled word "the". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Link: https://lore.kernel.org/r/20200707180414.10467-4-rdunlap@infradead.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-13kobject: documentation: Replace HTTP links with HTTPS onesAlexander A. Klimov
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Link: https://lore.kernel.org/r/20200713144103.35049-1-grandmaster@al2klimov.de Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-10Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netLinus Torvalds
Pull networking fixes from David Miller: 1) Restore previous behavior of CAP_SYS_ADMIN wrt loading networking BPF programs, from Maciej Żenczykowski. 2) Fix dropped broadcasts in mac80211 code, from Seevalamuthu Mariappan. 3) Slay memory leak in nl80211 bss color attribute parsing code, from Luca Coelho. 4) Get route from skb properly in ip_route_use_hint(), from Miaohe Lin. 5) Don't allow anything other than ARPHRD_ETHER in llc code, from Eric Dumazet. 6) xsk code dips too deeply into DMA mapping implementation internals. Add dma_need_sync and use it. From Christoph Hellwig 7) Enforce power-of-2 for BPF ringbuf sizes. From Andrii Nakryiko. 8) Check for disallowed attributes when loading flow dissector BPF programs. From Lorenz Bauer. 9) Correct packet injection to L3 tunnel devices via AF_PACKET, from Jason A. Donenfeld. 10) Don't advertise checksum offload on ipa devices that don't support it. From Alex Elder. 11) Resolve several issues in TCP MD5 signature support. Missing memory barriers, bogus options emitted when using syncookies, and failure to allow md5 key changes in established states. All from Eric Dumazet. 12) Fix interface leak in hsr code, from Taehee Yoo. 13) VF reset fixes in hns3 driver, from Huazhong Tan. 14) Make loopback work again with ipv6 anycast, from David Ahern. 15) Fix TX starvation under high load in fec driver, from Tobias Waldekranz. 16) MLD2 payload lengths not checked properly in bridge multicast code, from Linus Lüssing. 17) Packet scheduler code that wants to find the inner protocol currently only works for one level of VLAN encapsulation. Allow Q-in-Q situations to work properly here, from Toke Høiland-Jørgensen. 18) Fix route leak in l2tp, from Xin Long. 19) Resolve conflict between the sk->sk_user_data usage of bpf reuseport support and various protocols. From Martin KaFai Lau. 20) Fix socket cgroup v2 reference counting in some situations, from Cong Wang. 21) Cure memory leak in mlx5 connection tracking offload support, from Eli Britstein. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (146 commits) mlxsw: pci: Fix use-after-free in case of failed devlink reload mlxsw: spectrum_router: Remove inappropriate usage of WARN_ON() net: macb: fix call to pm_runtime in the suspend/resume functions net: macb: fix macb_suspend() by removing call to netif_carrier_off() net: macb: fix macb_get/set_wol() when moving to phylink net: macb: mark device wake capable when "magic-packet" property present net: macb: fix wakeup test in runtime suspend/resume routines bnxt_en: fix NULL dereference in case SR-IOV configuration fails libbpf: Fix libbpf hashmap on (I)LP32 architectures net/mlx5e: CT: Fix memory leak in cleanup net/mlx5e: Fix port buffers cell size value net/mlx5e: Fix 50G per lane indication net/mlx5e: Fix CPU mapping after function reload to avoid aRFS RX crash net/mlx5e: Fix VXLAN configuration restore after function reload net/mlx5e: Fix usage of rcu-protected pointer net/mxl5e: Verify that rpriv is not NULL net/mlx5: E-Switch, Fix vlan or qos setting in legacy mode net/mlx5: Fix eeprom support for SFP module cgroup: Fix sock_cgroup_data on big-endian. selftests: bpf: Fix detach from sockmap tests ...
2020-07-03Replace HTTP links with HTTPS ones: vsprintfAlexander A. Klimov
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200702200536.13389-1-grandmaster@al2klimov.de
2020-06-30dma-mapping: Add a new dma_need_sync APIChristoph Hellwig
Add a new API to check if calls to dma_sync_single_for_{device,cpu} are required for a given DMA streaming mapping. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200629130359.2690853-2-hch@lst.de
2020-06-26docs: move other kAPI documents to core-apiMauro Carvalho Chehab
There are a number of random documents that seem to be describing some aspects of the core-api. Move them to such directory, adding them at the core-api/index.rst file. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/86d979ed183adb76af93a92f20189bccf97f0055.1592918949.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-26docs: fix references for DMA*.txt filesMauro Carvalho Chehab
As we moved those files to core-api, fix references to point to their newer locations. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/37b2fd159fbc7655dbf33b3eb1215396a25f6344.1592895969.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-26docs: mm/gup: minor documentation updateSouptick Joarder
Now there are 5 cases. Updated the same. Link: http://lkml.kernel.org/r/1592422023-7401-1-git-send-email-jrdr.linux@gmail.com Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Jan Kara <jack@suse.cz> Cc: 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>
2020-06-19docs: mm/gup: Minor documentation updateSouptick Joarder
Now there are 5 cases. Updated the same. Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Link: https://lore.kernel.org/r/1592422023-7401-1-git-send-email-jrdr.linux@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-10Merge tag 'docs-5.8-2' of git://git.lwn.net/linuxLinus Torvalds
Pull more documentation updates from Jonathan Corbet: "A handful of late-arriving docs fixes, along with a patch changing a lot of HTTP links to HTTPS that had to be yanked and redone before the first pull" * tag 'docs-5.8-2' of git://git.lwn.net/linux: docs/memory-barriers.txt/kokr: smp_mb__{before,after}_atomic(): update Documentation Documentation: devres: add missing entry for devm_platform_get_and_ioremap_resource() Replace HTTP links with HTTPS ones: documentation docs: it_IT: address invalid reference warnings doc: zh_CN: use doc reference to resolve undefined label warning docs: Update the location of the LF NDA program docs: dev-tools: coccinelle: underlines
2020-06-08docs: mm/gup: pin_user_pages.rst: add a "case 5"John Hubbard
Patch series "vhost, docs: convert to pin_user_pages(), new "case 5"" It recently became clear to me that there are some get_user_pages*() callers that don't fit neatly into any of the four cases that are so far listed in pin_user_pages.rst. vhost.c is one of those. Add a Case 5 to the documentation, and refer to that when converting vhost.c. Thanks to Jan Kara for helping me (again) in understanding the interaction between get_user_pages() and page writeback [1]. This is based on today's mmotm, which has a nearby patch to pin_user_pages.rst that rewords cases 3 and 4. Note that I have only compile-tested the vhost.c patch, although that does also include cross-compiling for a few other arches. Any run-time testing would be greatly appreciated. [1] https://lore.kernel.org/r/20200529070343.GL14550@quack2.suse.cz This patch (of 2): There are four cases listed in pin_user_pages.rst. These are intended to help developers figure out whether to use get_user_pages*(), or pin_user_pages*(). However, the four cases do not cover all the situations. For example, drivers/vhost/vhost.c has a "pin, write to page, set page dirty, unpin" case. Add a fifth case, to help explain that there is a general pattern that requires pin_user_pages*() API calls. [jhubbard@nvidia.com: v2] Link: http://lkml.kernel.org/r/20200601052633.853874-2-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: "Michael S . Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Link: http://lkml.kernel.org/r/20200529234309.484480-1-jhubbard@nvidia.com Link: http://lkml.kernel.org/r/20200529234309.484480-2-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08mm/gup: update pin_user_pages.rst for "case 3" (mmu notifiers)John Hubbard
Update case 3 so that it covers the use of mmu notifiers, for hardware that does, or does not have replayable page faults. Also, elaborate case 4 slightly, as it was quite cryptic. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Jonathan Corbet <corbet@lwn.net> Link: http://lkml.kernel.org/r/20200527194953.11130-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08Replace HTTP links with HTTPS ones: documentationAlexander A. Klimov
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Link: https://lore.kernel.org/r/20200526060544.25127-1-grandmaster@al2klimov.de Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-03padata: document multithreaded jobsDaniel Jordan
Add Documentation for multithreaded jobs. Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Josh Triplett <josh@joshtriplett.org> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Robert Elliott <elliott@hpe.com> Cc: Shile Zhang <shile.zhang@linux.alibaba.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Tejun Heo <tj@kernel.org> Cc: Zi Yan <ziy@nvidia.com> Link: http://lkml.kernel.org/r/20200527173608.2885243-9-daniel.m.jordan@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-02Merge branch 'akpm' (patches from Andrew)Linus Torvalds
Merge updates from Andrew Morton: "A few little subsystems and a start of a lot of MM patches. Subsystems affected by this patch series: squashfs, ocfs2, parisc, vfs. With mm subsystems: slab-generic, slub, debug, pagecache, gup, swap, memcg, pagemap, memory-failure, vmalloc, kasan" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (128 commits) kasan: move kasan_report() into report.c mm/mm_init.c: report kasan-tag information stored in page->flags ubsan: entirely disable alignment checks under UBSAN_TRAP kasan: fix clang compilation warning due to stack protector x86/mm: remove vmalloc faulting mm: remove vmalloc_sync_(un)mappings() x86/mm/32: implement arch_sync_kernel_mappings() x86/mm/64: implement arch_sync_kernel_mappings() mm/ioremap: track which page-table levels were modified mm/vmalloc: track which page-table levels were modified mm: add functions to track page directory modifications s390: use __vmalloc_node in stack_alloc powerpc: use __vmalloc_node in alloc_vm_stack arm64: use __vmalloc_node in arch_alloc_vmap_stack mm: remove vmalloc_user_node_flags mm: switch the test_vmalloc module to use __vmalloc_node mm: remove __vmalloc_node_flags_caller mm: remove both instances of __vmalloc_node_flags mm: remove the prot argument to __vmalloc_node mm: remove the pgprot argument to __vmalloc ...
2020-06-02mm: remove map_vm_rangeChristoph Hellwig
Switch all callers to map_kernel_range, which symmetric to the unmap side (as well as the _noflush versions). Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: David Airlie <airlied@linux.ie> Cc: Gao Xiang <xiang@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Kelley <mikelley@microsoft.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Wei Liu <wei.liu@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mackerras <paulus@ozlabs.org> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will@kernel.org> Link: http://lkml.kernel.org/r/20200414131348.444715-17-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-01Merge tag 'docs-5.8' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation updates from Jonathan Corbet: "A fair amount of stuff this time around, dominated by yet another massive set from Mauro toward the completion of the RST conversion. I *really* hope we are getting close to the end of this. Meanwhile, those patches reach pretty far afield to update document references around the tree; there should be no actual code changes there. There will be, alas, more of the usual trivial merge conflicts. Beyond that we have more translations, improvements to the sphinx scripting, a number of additions to the sysctl documentation, and lots of fixes" * tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits) Documentation: fixes to the maintainer-entry-profile template zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst tracing: Fix events.rst section numbering docs: acpi: fix old http link and improve document format docs: filesystems: add info about efivars content Documentation: LSM: Correct the basic LSM description mailmap: change email for Ricardo Ribalda docs: sysctl/kernel: document unaligned controls Documentation: admin-guide: update bug-hunting.rst docs: sysctl/kernel: document ngroups_max nvdimm: fixes to maintainter-entry-profile Documentation/features: Correct RISC-V kprobes support entry Documentation/features: Refresh the arch support status files Revert "docs: sysctl/kernel: document ngroups_max" docs: move locking-specific documents to locking/ docs: move digsig docs to the security book docs: move the kref doc into the core-api book docs: add IRQ documentation at the core-api book docs: debugging-via-ohci1394.txt: add it to the core-api book docs: fix references for ipmi.rst file ...
2020-06-01Merge tag 'x86-build-2020-06-01' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 build updates from Ingo Molnar: "Misc dependency fixes, plus a documentation update about memory protection keys support" * tag 'x86-build-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/Kconfig: Update config and kernel doc for MPK feature on AMD x86/boot: Discard .discard.unreachable for arch/x86/boot/compressed/vmlinux x86/boot/build: Add phony targets in arch/x86/boot/Makefile to PHONY x86/boot/build: Make 'make bzlilo' not depend on vmlinux or $(obj)/bzImage x86/boot/build: Add cpustr.h to targets and remove clean-files
2020-06-01Merge tag 'printk-for-5.8' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Benjamin Herrenschmidt solved a problem with non-matched console aliases by first checking consoles defined on the command line. It is a more conservative approach than the previous attempts. - Benjamin also made sure that the console accessible via /dev/console always has CON_CONSDEV flag. - Andy Shevchenko added the %ptT modifier for printing struct time64_t. It extends the existing %ptR handling for struct rtc_time. - Bruno Meneguele fixed /dev/kmsg error value returned by unsupported SEEK_CUR. - Tetsuo Handa removed unused pr_cont_once(). ... and a few small fixes. * tag 'printk-for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk: Remove pr_cont_once() printk: handle blank console arguments passed in. kernel/printk: add kmsg SEEK_CUR handling printk: Fix a typo in comment "interator"->"iterator" usb: pulse8-cec: Switch to use %ptT ARM: bcm2835: Switch to use %ptT lib/vsprintf: Print time64_t in human readable format lib/vsprintf: update comment about simple_strto<foo>() functions printk: Correctly set CON_CONSDEV even when preferred console was not registered printk: Fix preferred console selection with multiple matches printk: Move console matching logic into a separate function printk: Convert a use of sprintf to snprintf in console_unlock
2020-05-28x86/Kconfig: Update config and kernel doc for MPK feature on AMDBabu Moger
AMD's next generation of EPYC processors support the MPK (Memory Protection Keys) feature. Update the dependency and documentation. Signed-off-by: Babu Moger <babu.moger@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lkml.kernel.org/r/159068199556.26992.17733929401377275140.stgit@naples-babu.amd.com
2020-05-20lib/vsprintf: Print time64_t in human readable formatAndy Shevchenko
There are users which print time and date represented by content of time64_t type in human readable format. Instead of open coding that each time introduce %ptT[dt][r] specifier. Few test cases for %ptT specifier has been added as well. Link: https://lore.kernel.org/r/20200415170046.33374-2-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Rewieved-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
2020-05-15docs: move the kref doc into the core-api bookMauro Carvalho Chehab
This document covers core kernel objects. So, add it into the core-api book. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/f385af13b4a6d3ff8c89beedd4506900e79ca72e.1588345503.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-15docs: add IRQ documentation at the core-api bookMauro Carvalho Chehab
There are 4 IRQ documentation files under Documentation/*.txt. Move them into a new directory (core-api/irq) and add a new index file for it. While here, use a title markup for the Debugging section of the irq-domain.rst file. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/2da7485c3718e1442e6b4c2dd66857b776e8899b.1588345503.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-15docs: debugging-via-ohci1394.txt: add it to the core-api bookMauro Carvalho Chehab
There is an special chapter inside the core-api book about some debug infrastructure like tracepoints and debug objects. It sounded to me that this is the best place to add a chapter explaining how to use a FireWire controller to do remote kernel debugging, as explained on this document. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/9b489d36d08ad89d3ad5aefef1f52a0715b29716.1588345503.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-15docs: move DMA kAPI to Documentation/core-apiMauro Carvalho Chehab
Move those files to the core-api, where they belong, renaming them to ReST and adding to the core API index file. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/a1517185418cb9d987f566ef85a5dd5c7c99f34e.1588345503.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-15bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifierDaniel Borkmann
Usage of plain %s conversion specifier in bpf_trace_printk() suffers from the very same issue as bpf_probe_read{,str}() helpers, that is, it is broken on archs with overlapping address ranges. While the helpers have been addressed through work in 6ae08ae3dea2 ("bpf: Add probe_read_{user, kernel} and probe_read_{user, kernel}_str helpers"), we need an option for bpf_trace_printk() as well to fix it. Similarly as with the helpers, force users to make an explicit choice by adding %pks and %pus specifier to bpf_trace_printk() which will then pick the corresponding strncpy_from_unsafe*() variant to perform the access under KERNEL_DS or USER_DS. The %pk* (kernel specifier) and %pu* (user specifier) can later also be extended for other objects aside strings that are probed and printed under tracing, and reused out of other facilities like bpf_seq_printf() or BTF based type printing. Existing behavior of %s for current users is still kept working for archs where it is not broken and therefore gated through CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE. For archs not having this property we fall-back to pick probing under KERNEL_DS as a sensible default. Fixes: 8d3b7dce8622 ("bpf: add support for %s specifier to bpf_trace_printk()") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-4-daniel@iogearbox.net
2020-05-05kobject: documentation: Fix erroneous function example in kobject doc.Qi Zheng
Update the definitions of some functions listed in the kobject document, since they have been changed. Signed-off-by: Qi Zheng <arch0.zheng@gmail.com> Link: https://lore.kernel.org/r/20200505061828.42952-1-arch0.zheng@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-21docs: Add rbtree documentation to the core-apiMatthew Wilcox (Oracle)
This file is close enough to being in rst format that I didn't feel the need to alter it in any way. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Michel Lespinasse <walken@google.com> Link: https://lore.kernel.org/r/20200401173343.17472-1-willy@infradead.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-20docs: pr_*() kerneldocs and basic printk docsRicardo Cañuelo
Add kerneldocs comments to the pr_*() macros in printk.h. Add a new rst node in the core-api manual describing the basic usage of printk and the related macro aliases. Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com> Link: https://lore.kernel.org/r/20200403093617.18003-1-ricardo.canuelo@collabora.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-15docs: timekeeping: Use correct prototype for deprecated functionsChris Packham
Use the correct prototypes for do_gettimeofday(), getnstimeofday() and getnstimeofday64(). All of these returned void and passed the return value by reference. This should make the documentation of their deprecation and replacements easier to search for. Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20200414221222.23996-1-chris.packham@alliedtelesis.co.nz Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-02mm: add pagemap.h to the fine documentationMatthew Wilcox (Oracle)
The documentation currently does not include the deathless prose written to describe functions in pagemap.h because it's not included in any rst file. Fix up the mismatches between parameter names and the documentation and add the file to mm-api. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Zi Yan <ziy@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Cc: Jonathan Corbet <corbet@lwn.net> Link: http://lkml.kernel.org/r/20200221220045.24989-1-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm: dump_page(): additional diagnostics for huge pinned pagesJohn Hubbard
As part of pin_user_pages() and related API calls, pages are "dma-pinned". For the case of compound pages of order > 1, the per-page accounting of dma pins is accomplished via the 3rd struct page in the compound page. In order to support debugging of any pin_user_pages()- related problems, enhance dump_page() so as to report the pin count in that case. Documentation/core-api/pin_user_pages.rst is also updated accordingly. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-13-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reportingJohn Hubbard
Now that pages are "DMA-pinned" via pin_user_page*(), and unpinned via unpin_user_pages*(), we need some visibility into whether all of this is working correctly. Add two new fields to /proc/vmstat: nr_foll_pin_acquired nr_foll_pin_released These are documented in Documentation/core-api/pin_user_pages.rst. They represent the number of pages (since boot time) that have been pinned ("nr_foll_pin_acquired") and unpinned ("nr_foll_pin_released"), via pin_user_pages*() and unpin_user_pages*(). In the absence of long-running DMA or RDMA operations that hold pages pinned, the above two fields will normally be equal to each other. Also: update Documentation/core-api/pin_user_pages.rst, to remove an earlier (now confirmed untrue) claim about a performance problem with /proc/vmstat. Also: update Documentation/core-api/pin_user_pages.rst to rename the new /proc/vmstat entries, to the names listed here. Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-9-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: page->hpage_pinned_refcount: exact pin counts for huge pagesJohn Hubbard
For huge pages (and in fact, any compound page), the GUP_PIN_COUNTING_BIAS scheme tends to overflow too easily, each tail page increments the head page->_refcount by GUP_PIN_COUNTING_BIAS (1024). That limits the number of huge pages that can be pinned. This patch removes that limitation, by using an exact form of pin counting for compound pages of order > 1. The "order > 1" is required because this approach uses the 3rd struct page in the compound page, and order 1 compound pages only have two pages, so that won't work there. A new struct page field, hpage_pinned_refcount, has been added, replacing a padding field in the union (so no new space is used). This enhancement also has a useful side effect: huge pages and compound pages (of order > 1) do not suffer from the "potential false positives" problem that is discussed in the page_dma_pinned() comment block. That is because these compound pages have extra space for tracking things, so they get exact pin counts instead of overloading page->_refcount. Documentation/core-api/pin_user_pages.rst is updated accordingly. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-8-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02mm/gup: track FOLL_PIN pagesJohn Hubbard
Add tracking of pages that were pinned via FOLL_PIN. This tracking is implemented via overloading of page->_refcount: pins are added by adding GUP_PIN_COUNTING_BIAS (1024) to the refcount. This provides a fuzzy indication of pinning, and it can have false positives (and that's OK). Please see the pre-existing Documentation/core-api/pin_user_pages.rst for details. As mentioned in pin_user_pages.rst, callers who effectively set FOLL_PIN (typically via pin_user_pages*()) are required to ultimately free such pages via unpin_user_page(). Please also note the limitation, discussed in pin_user_pages.rst under the "TODO: for 1GB and larger huge pages" section. (That limitation will be removed in a following patch.) The effect of a FOLL_PIN flag is similar to that of FOLL_GET, and may be thought of as "FOLL_GET for DIO and/or RDMA use". Pages that have been pinned via FOLL_PIN are identifiable via a new function call: bool page_maybe_dma_pinned(struct page *page); What to do in response to encountering such a page, is left to later patchsets. There is discussion about this in [1], [2], [3], and [4]. This also changes a BUG_ON(), to a WARN_ON(), in follow_page_mask(). [1] Some slow progress on get_user_pages() (Apr 2, 2019): https://lwn.net/Articles/784574/ [2] DMA and get_user_pages() (LPC: Dec 12, 2018): https://lwn.net/Articles/774411/ [3] The trouble with get_user_pages() (Apr 30, 2018): https://lwn.net/Articles/753027/ [4] LWN kernel index: get_user_pages(): https://lwn.net/Kernel/Index/#Memory_management-get_user_pages [jhubbard@nvidia.com: add kerneldoc] Link: http://lkml.kernel.org/r/20200307021157.235726-1-jhubbard@nvidia.com [imbrenda@linux.ibm.com: if pin fails, we need to unpin, a simple put_page will not be enough] Link: http://lkml.kernel.org/r/20200306132537.783769-2-imbrenda@linux.ibm.com [akpm@linux-foundation.org: fix put_compound_head defined but not used] Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-7-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-03-10docs: move core-api/ioctl.rst to driver-api/Jonathan Corbet
The ioctl() documentation belongs with the rest of the driver-oriented info, so move it there. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-03-10docs: move gcc-plugins to the kbuild manualJonathan Corbet
Information about GCC plugins is relevant to kernel building, so move this document to the kbuild manual. Acked-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-03-10docs: Organize core-api/index.rstJonathan Corbet
The core-api manual has become a big, disorganized mess. Try to bring a small amount of order to it by organizing the documents into subcategories. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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