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2025-07-08af_unix: Introduce SO_INQ.Kuniyuki Iwashima1-0/+3
We have an application that uses almost the same code for TCP and AF_UNIX (SOCK_STREAM). TCP can use TCP_INQ, but AF_UNIX doesn't have it and requires an extra syscall, ioctl(SIOCINQ) or getsockopt(SO_MEMINFO) as an alternative. Let's introduce the generic version of TCP_INQ. If SO_INQ is enabled, recvmsg() will put a cmsg of SCM_INQ that contains the exact value of ioctl(SIOCINQ). The cmsg is also included when msg->msg_get_inq is non-zero to make sockets io_uring-friendly. Note that SOCK_CUSTOM_SOCKOPT is flagged only for SOCK_STREAM to override setsockopt() for SOL_SOCKET. By having the flag in struct unix_sock, instead of struct sock, we can later add SO_INQ support for TCP and reuse tcp_sk(sk)->recvmsg_inq. Note also that supporting custom getsockopt() for SOL_SOCKET will need preparation for other SOCK_CUSTOM_SOCKOPT users (UDP, vsock, MPTCP). Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/20250702223606.1054680-7-kuniyu@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-05-23af_unix: Introduce SO_PASSRIGHTS.Kuniyuki Iwashima1-0/+2
As long as recvmsg() or recvmmsg() is used with cmsg, it is not possible to avoid receiving file descriptors via SCM_RIGHTS. This behaviour has occasionally been flagged as problematic, as it can be (ab)used to trigger DoS during close(), for example, by passing a FUSE-controlled fd or a hung NFS fd. For instance, as noted on the uAPI Group page [0], an untrusted peer could send a file descriptor pointing to a hung NFS mount and then close it. Once the receiver calls recvmsg() with msg_control, the descriptor is automatically installed, and then the responsibility for the final close() now falls on the receiver, which may result in blocking the process for a long time. Regarding this, systemd calls cmsg_close_all() [1] after each recvmsg() to close() unwanted file descriptors sent via SCM_RIGHTS. However, this cannot work around the issue at all, because the final fput() may still occur on the receiver's side once sendmsg() with SCM_RIGHTS succeeds. Also, even filtering by LSM at recvmsg() does not work for the same reason. Thus, we need a better way to refuse SCM_RIGHTS at sendmsg(). Let's introduce SO_PASSRIGHTS to disable SCM_RIGHTS. Note that this option is enabled by default for backward compatibility. Link: https://uapi-group.org/kernel-features/#disabling-reception-of-scm_rights-for-af_unix-sockets #[0] Link: https://github.com/systemd/systemd/blob/v257.5/src/basic/fd-util.c#L612-L628 #[1] Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2024-12-16sock: Introduce SO_RCVPRIORITY socket optionAnna Emese Nyiri1-0/+2
Add new socket option, SO_RCVPRIORITY, to include SO_PRIORITY in the ancillary data returned by recvmsg(). This is analogous to the existing support for SO_RCVMARK, as implemented in commit 6fd1d51cfa253 ("net: SO_RCVMARK socket option for SO_MARK with recvmsg()"). Reviewed-by: Willem de Bruijn <willemb@google.com> Suggested-by: Ferenc Fejes <fejes@inf.elte.hu> Signed-off-by: Anna Emese Nyiri <annaemesenyiri@gmail.com> Link: https://patch.msgid.link/20241213084457.45120-5-annaemesenyiri@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-11-23Merge tag 'mm-stable-2024-11-18-19-27' of ↵Linus Torvalds1-0/+3
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - The series "zram: optimal post-processing target selection" from Sergey Senozhatsky improves zram's post-processing selection algorithm. This leads to improved memory savings. - Wei Yang has gone to town on the mapletree code, contributing several series which clean up the implementation: - "refine mas_mab_cp()" - "Reduce the space to be cleared for maple_big_node" - "maple_tree: simplify mas_push_node()" - "Following cleanup after introduce mas_wr_store_type()" - "refine storing null" - The series "selftests/mm: hugetlb_fault_after_madv improvements" from David Hildenbrand fixes this selftest for s390. - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng implements some rationaizations and cleanups in the page mapping code. - The series "mm: optimize shadow entries removal" from Shakeel Butt optimizes the file truncation code by speeding up the handling of shadow entries. - The series "Remove PageKsm()" from Matthew Wilcox completes the migration of this flag over to being a folio-based flag. - The series "Unify hugetlb into arch_get_unmapped_area functions" from Oscar Salvador implements a bunch of consolidations and cleanups in the hugetlb code. - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain takes away the wp-fault time practice of turning a huge zero page into small pages. Instead we replace the whole thing with a THP. More consistent cleaner and potentiall saves a large number of pagefaults. - The series "percpu: Add a test case and fix for clang" from Andy Shevchenko enhances and fixes the kernel's built in percpu test code. - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett optimizes mremap() by avoiding doing things which we didn't need to do. - The series "Improve the tmpfs large folio read performance" from Baolin Wang teaches tmpfs to copy data into userspace at the folio size rather than as individual pages. A 20% speedup was observed. - The series "mm/damon/vaddr: Fix issue in damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting. - The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt removes the long-deprecated memcgv2 charge moving feature. - The series "fix error handling in mmap_region() and refactor" from Lorenzo Stoakes cleanup up some of the mmap() error handling and addresses some potential performance issues. - The series "x86/module: use large ROX pages for text allocations" from Mike Rapoport teaches x86 to use large pages for read-only-execute module text. - The series "page allocation tag compression" from Suren Baghdasaryan is followon maintenance work for the new page allocation profiling feature. - The series "page->index removals in mm" from Matthew Wilcox remove most references to page->index in mm/. A slow march towards shrinking struct page. - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs interface tests" from Andrew Paniakin performs maintenance work for DAMON's self testing code. - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar improves zswap's batching of compression and decompression. It is a step along the way towards using Intel IAA hardware acceleration for this zswap operation. - The series "kasan: migrate the last module test to kunit" from Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests over to the KUnit framework. - The series "implement lightweight guard pages" from Lorenzo Stoakes permits userapace to place fault-generating guard pages within a single VMA, rather than requiring that multiple VMAs be created for this. Improved efficiencies for userspace memory allocators are expected. - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses tracepoints to provide increased visibility into memcg stats flushing activity. - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky fixes a zram buglet which potentially affected performance. - The series "mm: add more kernel parameters to control mTHP" from Maíra Canal enhances our ability to control/configuremultisize THP from the kernel boot command line. - The series "kasan: few improvements on kunit tests" from Sabyrzhan Tasbolatov has a couple of fixups for the KASAN KUnit tests. - The series "mm/list_lru: Split list_lru lock into per-cgroup scope" from Kairui Song optimizes list_lru memory utilization when lockdep is enabled. * tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits) cma: enforce non-zero pageblock_order during cma_init_reserved_mem() mm/kfence: add a new kunit test test_use_after_free_read_nofault() zram: fix NULL pointer in comp_algorithm_show() memcg/hugetlb: add hugeTLB counters to memcg vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount zram: ZRAM_DEF_COMP should depend on ZRAM MAINTAINERS/MEMORY MANAGEMENT: add document files for mm Docs/mm/damon: recommend academic papers to read and/or cite mm: define general function pXd_init() kmemleak: iommu/iova: fix transient kmemleak false positive mm/list_lru: simplify the list_lru walk callback function mm/list_lru: split the lock to per-cgroup scope mm/list_lru: simplify reparenting and initial allocation mm/list_lru: code clean up for reparenting mm/list_lru: don't export list_lru_add mm/list_lru: don't pass unnecessary key parameters kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols ...
2024-11-11mm: madvise: implement lightweight guard page mechanismLorenzo Stoakes1-0/+3
Implement a new lightweight guard page feature, that is regions of userland virtual memory that, when accessed, cause a fatal signal to arise. Currently users must establish PROT_NONE ranges to achieve this. However this is very costly memory-wise - we need a VMA for each and every one of these regions AND they become unmergeable with surrounding VMAs. In addition repeated mmap() calls require repeated kernel context switches and contention of the mmap lock to install these ranges, potentially also having to unmap memory if installed over existing ranges. The lightweight guard approach eliminates the VMA cost altogether - rather than establishing a PROT_NONE VMA, it operates at the level of page table entries - establishing PTE markers such that accesses to them cause a fault followed by a SIGSGEV signal being raised. This is achieved through the PTE marker mechanism, which we have already extended to provide PTE_MARKER_GUARD, which we installed via the generic page walking logic which we have extended for this purpose. These guard ranges are established with MADV_GUARD_INSTALL. If the range in which they are installed contain any existing mappings, they will be zapped, i.e. free the range and unmap memory (thus mimicking the behaviour of MADV_DONTNEED in this respect). Any existing guard entries will be left untouched. There is therefore no nesting of guarded pages. Guarded ranges are NOT cleared by MADV_DONTNEED nor MADV_FREE (in both instances the memory range may be reused at which point a user would expect guards to still be in place), but they are cleared via MADV_GUARD_REMOVE, process teardown or unmapping of memory ranges. The guard property can be removed from ranges via MADV_GUARD_REMOVE. The ranges over which this is applied, should they contain non-guard entries, will be untouched, with only guard entries being cleared. We permit this operation on anonymous memory only, and only VMAs which are non-special, non-huge and not mlock()'d (if we permitted this we'd have to drop locked pages which would be rather counterintuitive). Racing page faults can cause repeated attempts to install guard pages that are interrupted, result in a zap, and this process can end up being repeated. If this happens more than would be expected in normal operation, we rescind locks and retry the whole thing, which avoids lock contention in this scenario. Link: https://lkml.kernel.org/r/6aafb5821bf209f277dfae0787abb2ef87a37542.1730123433.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Suggested-by: Jann Horn <jannh@google.com> Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Suggested-by: Jann Horn <jannh@google.com> Suggested-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Arnd Bergmann <arnd@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chris Zankel <chris@zankel.net> Cc: Helge Deller <deller@gmx.de> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Jeff Xu <jeffxu@chromium.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-10-04net_tstamp: add SCM_TS_OPT_ID to provide OPT_ID in control messageVadim Fedorenko1-0/+2
SOF_TIMESTAMPING_OPT_ID socket option flag gives a way to correlate TX timestamps and packets sent via socket. Unfortunately, there is no way to reliably predict socket timestamp ID value in case of error returned by sendmsg. For UDP sockets it's impossible because of lockless nature of UDP transmit, several threads may send packets in parallel. In case of RAW sockets MSG_MORE option makes things complicated. More details are in the conversation [1]. This patch adds new control message type to give user-space software an opportunity to control the mapping between packets and values by providing ID with each sendmsg for UDP sockets. The documentation is also added in this patch. [1] https://lore.kernel.org/netdev/CALCETrU0jB+kg0mhV6A8mrHfTE1D1pr1SD_B9Eaa9aDPfgHdtA@mail.gmail.com/ Reviewed-by: Willem de Bruijn <willemb@google.com> Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> Signed-off-by: Vadim Fedorenko <vadfed@meta.com> Link: https://patch.msgid.link/20241001125716.2832769-2-vadfed@meta.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-09-16Merge tag 'mips_6.12' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux Pull MIPS updates from Thomas Bogendoerfer: - use devm_clk_get_enabled() helper - prototype fixes - cleanup unused stuff * tag 'mips_6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: mips: Remove posix_types.h include from sigcontext.h bus: bt1-apb: change to use devm_clk_get_enabled() helper bus: bt1-axi: change to use devm_clk_get_enabled() helper MIPS: dec: prom: Remove unused unregister_prom_console() declaration MIPS: Remove unused mips_display/_scroll_message() declarations MIPS: Remove unused declarations in asm/cmp.h MIPS: MT: Remove unused function mips_mt_regdump() mips/jazz: remove unused jazz_handle_int() declaration MIPS: Remove unused function dump_au1000_dma_channel() in dma.c MIPS: ralink: Fix missing `get_c0_perfcount_int` prototype MIPS: ralink: Fix missing `plat_time_init` prototype
2024-09-11net: add SO_DEVMEM_DONTNEED setsockopt to release RX fragsMina Almasry1-0/+1
Add an interface for the user to notify the kernel that it is done reading the devmem dmabuf frags returned as cmsg. The kernel will drop the reference on the frags to make them available for reuse. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com> Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20240910171458.219195-11-almasrymina@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-09-11tcp: RX path for devmem TCPMina Almasry1-0/+5
In tcp_recvmsg_locked(), detect if the skb being received by the user is a devmem skb. In this case - if the user provided the MSG_SOCK_DEVMEM flag - pass it to tcp_recvmsg_devmem() for custom handling. tcp_recvmsg_devmem() copies any data in the skb header to the linear buffer, and returns a cmsg to the user indicating the number of bytes returned in the linear buffer. tcp_recvmsg_devmem() then loops over the unaccessible devmem skb frags, and returns to the user a cmsg_devmem indicating the location of the data in the dmabuf device memory. cmsg_devmem contains this information: 1. the offset into the dmabuf where the payload starts. 'frag_offset'. 2. the size of the frag. 'frag_size'. 3. an opaque token 'frag_token' to return to the kernel when the buffer is to be released. The pages awaiting freeing are stored in the newly added sk->sk_user_frags, and each page passed to userspace is get_page()'d. This reference is dropped once the userspace indicates that it is done reading this page. All pages are released when the socket is destroyed. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com> Signed-off-by: Mina Almasry <almasrymina@google.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20240910171458.219195-10-almasrymina@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-08-29mips: Remove posix_types.h include from sigcontext.hXi Ruoyao1-1/+0
Nothing in sigcontext.h seems to require anything from linux/posix_types.h. It seems only a relict: in a Linux 2.6.11-rc2 patch [1] the linux/types.h include was unexplainedly changed to a linux/posix_types.h include. I can only assume it was just an error. Finally headers_check complained "found __[us]{8,16,32,64} type without #include <linux/types.h>" and commit ae612fb05b0f ("headers_check fix: mips, sigcontext.h") added back the linux/types.h include, but it didn't remove the posix_types.h include. Remove it now. [1]:https://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11-rc2/2.6.11-rc2-mm2/broken-out/mips-generic-mips-updates.patch Signed-off-by: Xi Ruoyao <xry111@xry111.site> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2024-02-08kvm: replace __KVM_HAVE_READONLY_MEM with Kconfig symbolPaolo Bonzini1-2/+0
KVM uses __KVM_HAVE_* symbols in the architecture-dependent uapi/asm/kvm.h to mask unused definitions in include/uapi/linux/kvm.h. __KVM_HAVE_READONLY_MEM however was nothing but a misguided attempt to define KVM_CAP_READONLY_MEM only on architectures where KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM) could possibly return nonzero. This however does not make sense, and it prevented userspace from supporting this architecture-independent feature without recompilation. Therefore, these days __KVM_HAVE_READONLY_MEM does not mask anything and is only used in virt/kvm/kvm_main.c. Userspace does not need to test it and there should be no need for it to exist. Remove it and replace it with a Kconfig symbol within Linux source code. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-01-08MIPS: Fix typosBjorn Helgaas2-2/+2
Fix typos, most reported by "codespell arch/mips". Only touches comments, no code changes. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: linux-mips@vger.kernel.org Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2023-06-29Merge tag 'mips_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linuxLinus Torvalds1-0/+33
Pull MIPS updates from Thomas Bogendoerfer: - add support for TP-Link HC220 G5 v1 - add support for Wifi/Bluetooth on CI20 - rework Ralink clock and reset handling - cleanups and fixes * tag 'mips_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (58 commits) MIPS: Loongson64: DTS: Add RTC support to Loongson-2K1000 MIPS: Loongson64: DTS: Add RTC support to LS7A PCH MIPS: OCTEON: octeon-usb: cleanup divider calculation MIPS: OCTEON: octeon-usb: introduce dwc3_octeon_{read,write}q MIPS: OCTEON: octeon-usb: move gpio config to separate function MIPS: OCTEON: octeon-usb: use bitfields for shim register MIPS: OCTEON: octeon-usb: use bitfields for host config register MIPS: OCTEON: octeon-usb: use bitfields for control register MIPS: OCTEON: octeon-usb: add all register offsets mips: ralink: match all supported system controller compatible strings MIPS: dec: prom: Address -Warray-bounds warning MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts clk: ralink: mtmips: Fix uninitialized use of ret in mtmips_register_{fixed,factor}_clocks() mips: ralink: introduce commonly used remap node function mips: pci-mt7620: use dev_info() to log PCIe device detection result mips: pci-mt7620: do not print NFTS register value as error log MAINTAINERS: add Mediatek MTMIPS Clock maintainer mips: ralink: get cpu rate from new driver code mips: ralink: remove reset related code mips: ralink: mt7620: remove clock related code ...
2023-06-12net: core: add getsockopt SO_PEERPIDFDAlexander Mikhalitsyn1-0/+1
Add SO_PEERPIDFD which allows to get pidfd of peer socket holder pidfd. This thing is direct analog of SO_PEERCRED which allows to get plain PID. Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: David Ahern <dsahern@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kees Cook <keescook@chromium.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Luca Boccassi <bluca@debian.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Stanislav Fomichev <sdf@google.com> Cc: bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-arch@vger.kernel.org Reviewed-by: Christian Brauner <brauner@kernel.org> Acked-by: Stanislav Fomichev <sdf@google.com> Tested-by: Luca Boccassi <bluca@debian.org> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-12scm: add SO_PASSPIDFD and SCM_PIDFDAlexander Mikhalitsyn1-0/+2
Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS, but it contains pidfd instead of plain pid, which allows programmers not to care about PID reuse problem. We mask SO_PASSPIDFD feature if CONFIG_UNIX is not builtin because it depends on a pidfd_prepare() API which is not exported to the kernel modules. Idea comes from UAPI kernel group: https://uapi-group.org/kernel-features/ Big thanks to Christian Brauner and Lennart Poettering for productive discussions about this. Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Leon Romanovsky <leon@kernel.org> Cc: David Ahern <dsahern@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kees Cook <keescook@chromium.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: Lennart Poettering <mzxreary@0pointer.de> Cc: Luca Boccassi <bluca@debian.org> Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-arch@vger.kernel.org Tested-by: Luca Boccassi <bluca@debian.org> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2023-06-09MIPS: uaccess: emulate Ingenic LXW/LXH/LXHU uaccessSiarhei Volkau1-0/+33
The LXW, LXH, LXHU opcodes are part of the MXU ASE found in Ingenic XBurst based SoCs. While technically part of the MXU ASE, they do not touch any of the SIMD registers, and can be used even when the MXU ASE is disabled. This patch makes it possible to emulate unaligned access for those instructions. Signed-off-by: Siarhei Volkau <lis8215@gmail.com> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2022-09-11mm/madvise: introduce MADV_COLLAPSE sync hugepage collapseZach O'Keefe1-0/+2
This idea was introduced by David Rientjes[1]. Introduce a new madvise mode, MADV_COLLAPSE, that allows users to request a synchronous collapse of memory at their own expense. The benefits of this approach are: * CPU is charged to the process that wants to spend the cycles for the THP * Avoid unpredictable timing of khugepaged collapse Semantics This call is independent of the system-wide THP sysfs settings, but will fail for memory marked VM_NOHUGEPAGE. If the ranges provided span multiple VMAs, the semantics of the collapse over each VMA is independent from the others. This implies a hugepage cannot cross a VMA boundary. If collapse of a given hugepage-aligned/sized region fails, the operation may continue to attempt collapsing the remainder of memory specified. The memory ranges provided must be page-aligned, but are not required to be hugepage-aligned. If the memory ranges are not hugepage-aligned, the start/end of the range will be clamped to the first/last hugepage-aligned address covered by said range. The memory ranges must span at least one hugepage-sized region. All non-resident pages covered by the range will first be swapped/faulted-in, before being internally copied onto a freshly allocated hugepage. Unmapped pages will have their data directly initialized to 0 in the new hugepage. However, for every eligible hugepage aligned/sized region to-be collapsed, at least one page must currently be backed by memory (a PMD covering the address range must already exist). Allocation for the new hugepage may enter direct reclaim and/or compaction, regardless of VMA flags. When the system has multiple NUMA nodes, the hugepage will be allocated from the node providing the most native pages. This operation operates on the current state of the specified process and makes no persistent changes or guarantees on how pages will be mapped, constructed, or faulted in the future Return Value If all hugepage-sized/aligned regions covered by the provided range were either successfully collapsed, or were already PMD-mapped THPs, this operation will be deemed successful. On success, process_madvise(2) returns the number of bytes advised, and madvise(2) returns 0. Else, -1 is returned and errno is set to indicate the error for the most-recently attempted hugepage collapse. Note that many failures might have occurred, since the operation may continue to collapse in the event a single hugepage-sized/aligned region fails. ENOMEM Memory allocation failed or VMA not found EBUSY Memcg charging failed EAGAIN Required resource temporarily unavailable. Try again might succeed. EINVAL Other error: No PMD found, subpage doesn't have Present bit set, "Special" page no backed by struct page, VMA incorrectly sized, address not page-aligned, ... Most notable here is ENOMEM and EBUSY (new to madvise) which are intended to provide the caller with actionable feedback so they may take an appropriate fallback measure. Use Cases An immediate user of this new functionality are malloc() implementations that manage memory in hugepage-sized chunks, but sometimes subrelease memory back to the system in native-sized chunks via MADV_DONTNEED; zapping the pmd. Later, when the memory is hot, the implementation could madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain hugepage coverage and dTLB performance. TCMalloc is such an implementation that could benefit from this[2]. Only privately-mapped anon memory is supported for now, but additional support for file, shmem, and HugeTLB high-granularity mappings[2] is expected. File and tmpfs/shmem support would permit: * Backing executable text by THPs. Current support provided by CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large system which might impair services from serving at their full rated load after (re)starting. Tricks like mremap(2)'ing text onto anonymous memory to immediately realize iTLB performance prevents page sharing and demand paging, both of which increase steady state memory footprint. With MADV_COLLAPSE, we get the best of both worlds: Peak upfront performance and lower RAM footprints. * Backing guest memory by hugapages after the memory contents have been migrated in native-page-sized chunks to a new host, in a userfaultfd-based live-migration stack. [1] https://lore.kernel.org/linux-mm/d098c392-273a-36a4-1a29-59731cdf5d3d@google.com/ [2] https://github.com/google/tcmalloc/tree/master/tcmalloc [jrdr.linux@gmail.com: avoid possible memory leak in failure path] Link: https://lkml.kernel.org/r/20220713024109.62810-1-jrdr.linux@gmail.com [zokeefe@google.com add missing kfree() to madvise_collapse()] Link: https://lore.kernel.org/linux-mm/20220713024109.62810-1-jrdr.linux@gmail.com/ Link: https://lkml.kernel.org/r/20220713161851.1879439-1-zokeefe@google.com [zokeefe@google.com: delay computation of hpage boundaries until use]] Link: https://lkml.kernel.org/r/20220720140603.1958773-4-zokeefe@google.com Link: https://lkml.kernel.org/r/20220706235936.2197195-10-zokeefe@google.com Signed-off-by: Zach O'Keefe <zokeefe@google.com> Signed-off-by: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com> Suggested-by: David Rientjes <rientjes@google.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Chris Kennelly <ckennelly@google.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Hildenbrand <david@redhat.com> Cc: Helge Deller <deller@gmx.de> Cc: Hugh Dickins <hughd@google.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavel Begunkov <asml.silence@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-28treewide: uapi: Replace zero-length arrays with flexible-array membersGustavo A. R. Silva1-1/+1
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. This code was transformed with the help of Coccinelle: (linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch) @@ identifier S, member, array; type T1, T2; @@ struct S { ... T1 member; T2 array[ - 0 ]; }; -fstrict-flex-arrays=3 is coming and we need to land these changes to prevent issues like these in the short future: ../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0, but the source string has length 2 (including NUL byte) [-Wfortify-source] strcpy(de3->name, "."); ^ Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If this breaks anything, we can use a union with a new member name. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays Link: https://github.com/KSPP/linux/issues/78 Build-tested-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/ Acked-by: Dan Williams <dan.j.williams@intel.com> # For ndctl.h Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2022-06-03Merge tag 'tty-5.19-rc1' of ↵Linus Torvalds1-150/+99
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty and serial driver updates from Greg KH: "Here is the big set of tty and serial driver updates for 5.19-rc1. Lots of tiny cleanups in here, the major stuff is: - termbit cleanups and unification by Ilpo. A much needed change that goes a long way to making things simpler for all of the different arches - tty documentation cleanups and movements to their own place in the documentation tree - old tty driver cleanups and fixes from Jiri to bring some existing drivers into the modern world - RS485 cleanups and unifications to make it easier for individual drivers to support this mode instead of having to duplicate logic in each driver - Lots of 8250 driver updates and additions - new device id additions - n_gsm continued fixes and cleanups - other minor serial driver updates and cleanups All of these have been in linux-next for weeks with no reported issues" * tag 'tty-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (166 commits) tty: Rework receive flow control char logic pcmcia: synclink_cs: Don't allow CS5-6 serial: stm32-usart: Correct CSIZE, bits, and parity serial: st-asc: Sanitize CSIZE and correct PARENB for CS7 serial: sifive: Sanitize CSIZE and c_iflag serial: sh-sci: Don't allow CS5-6 serial: txx9: Don't allow CS5-6 serial: rda-uart: Don't allow CS5-6 serial: digicolor-usart: Don't allow CS5-6 serial: uartlite: Fix BRKINT clearing serial: cpm_uart: Fix build error without CONFIG_SERIAL_CPM_CONSOLE serial: core: Do stop_rx in suspend path for console if console_suspend is disabled tty: serial: qcom-geni-serial: Remove uart frequency table. Instead, find suitable frequency with call to clk_round_rate. dt-bindings: serial: renesas,em-uart: Add RZ/V2M clock to access the registers serial: 8250_fintek: Check SER_RS485_RTS_* only with RS485 Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL" serial: msm_serial: disable interrupts in __msm_console_write() serial: meson: acquire port->lock in startup() serial: 8250_dw: Use dev_err_probe() serial: 8250_dw: Use devm_add_action_or_reset() ...
2022-06-02Merge tag 'asm-generic-fixes-5.19' of ↵Linus Torvalds1-6/+6
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic Pull asm-generic fixes from Arnd Bergmann: "The header cleanup series from Masahiro Yamada ended up causing some regressions in the ABI because of an ambigous uid_t type. This was only caught after the original patches got merged, but at least the fixes are trivial and hopefully complete" * tag 'asm-generic-fixes-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: binder: fix sender_euid type in uapi header sparc: fix mis-use of __kernel_{uid,gid}_t in uapi/asm/stat.h powerpc: use __kernel_{uid,gid}32_t in uapi/asm/stat.h mips: use __kernel_{uid,gid}32_t in uapi/asm/stat.h
2022-06-02mips: use __kernel_{uid,gid}32_t in uapi/asm/stat.hMasahiro Yamada1-6/+6
Commit 8c1a381a4fbb ("mips: add asm/stat.h to UAPI compile-test coverage") converted as follows: uid_t --> __kernel_uid_t gid_t --> __kernel_gid_t The bit width of __kernel_{uid,gid}_t is 16 or 32-bits depending on architectures. MIPS uses 32-bits for them as in include/uapi/asm-generic/posix_types.h, so the previous conversion is probably fine, but let's stick to the arch-independent conversion just in case. The safe replacements across all architectures are: uid_t --> __kernel_uid32_t gid_t --> __kernel_gid32_t as defined in include/linux/types.h. A similar issue was reported for the android binder. [1] [1]: https://lore.kernel.org/all/20220601010017.2639048-1-cmllamas@google.com/ Fixes: 8c1a381a4fbb ("mips: add asm/stat.h to UAPI compile-test coverage") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2022-05-31Merge tag 'riscv-for-linus-5.19-mw0' of ↵Linus Torvalds1-25/+5
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - Support for the Svpbmt extension, which allows memory attributes to be encoded in pages - Support for the Allwinner D1's implementation of page-based memory attributes - Support for running rv32 binaries on rv64 systems, via the compat subsystem - Support for kexec_file() - Support for the new generic ticket-based spinlocks, which allows us to also move to qrwlock. These should have already gone in through the asm-geneic tree as well - A handful of cleanups and fixes, include some larger ones around atomics and XIP * tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits) RISC-V: Prepare dropping week attribute from arch_kexec_apply_relocations[_add] riscv: compat: Using seperated vdso_maps for compat_vdso_info RISC-V: Fix the XIP build RISC-V: Split out the XIP fixups into their own file RISC-V: ignore xipImage RISC-V: Avoid empty create_*_mapping definitions riscv: Don't output a bogus mmu-type on a no MMU kernel riscv: atomic: Add custom conditional atomic operation implementation riscv: atomic: Optimize dec_if_positive functions riscv: atomic: Cleanup unnecessary definition RISC-V: Load purgatory in kexec_file RISC-V: Add purgatory RISC-V: Support for kexec_file on panic RISC-V: Add kexec_file support RISC-V: use memcpy for kexec_file mode kexec_file: Fix kexec_file.c build error for riscv platform riscv: compat: Add COMPAT Kbuild skeletal support riscv: compat: ptrace: Add compat_arch_ptrace implement riscv: compat: signal: Add rt_frame implementation riscv: add memory-type errata for T-Head ...
2022-05-26Merge tag 'asm-generic-5.19' of ↵Linus Torvalds1-10/+10
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic Pull asm-generic updates from Arnd Bergmann: "The asm-generic tree contains three separate changes for linux-5.19: - The h8300 architecture is retired after it has been effectively unmaintained for a number of years. This is the last architecture we supported that has no MMU implementation, but there are still a few architectures (arm, m68k, riscv, sh and xtensa) that support CPUs with and without an MMU. - A series to add a generic ticket spinlock that can be shared by most architectures with a working cmpxchg or ll/sc type atomic, including the conversion of riscv, csky and openrisc. This series is also a prerequisite for the loongarch64 architecture port that will come as a separate pull request. - A cleanup of some exported uapi header files to ensure they can be included from user space without relying on other kernel headers" * tag 'asm-generic-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: h8300: remove stale bindings and symlink sparc: add asm/stat.h to UAPI compile-test coverage powerpc: add asm/stat.h to UAPI compile-test coverage mips: add asm/stat.h to UAPI compile-test coverage riscv: add linux/bpf_perf_event.h to UAPI compile-test coverage kbuild: prevent exported headers from including <stdlib.h>, <stdbool.h> agpgart.h: do not include <stdlib.h> from exported header csky: Move to generic ticket-spinlock RISC-V: Move to queued RW locks RISC-V: Move to generic spinlocks openrisc: Move to ticket-spinlock asm-generic: qrwlock: Document the spinlock fairness requirements asm-generic: qspinlock: Indicate the use of mixed-size atomics asm-generic: ticket-lock: New generic ticket-based spinlock remove the h8300 architecture
2022-05-19termbits.h: Remove posix_types.h includeIlpo Järvinen1-2/+0
Nothing in termbits seems to require anything from linux/posix_types.h. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220509093446.6677-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-19termbits.h: Align lines & formatIlpo Järvinen1-78/+78
- Align c_cc defines. - Remove extra newlines. - Realign & adjust number of leading zeros. - Reorder c_cflag defines to ascending order - Make comment ending shorted (=remove period and one extra space from the comments in mips). Co-developed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220509093446.6677-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-19termbits.h: create termbits-common.h for identical bitsIlpo Järvinen1-51/+2
Some defines are the same across all archs. Move the most obvious intersection to termbits-common.h. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220509093446.6677-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-13mips: add asm/stat.h to UAPI compile-test coverageMasahiro Yamada1-10/+10
asm/stat.h is currently excluded from the UAPI compile-test for ARCH=mips because of the errors like follows: HDRTEST usr/include/asm/stat.h In file included from <command-line>:32: ./usr/include/asm/stat.h:22:2: error: unknown type name 'ino_t' 22 | ino_t st_ino; | ^~~~~ ./usr/include/asm/stat.h:23:2: error: unknown type name 'mode_t' 23 | mode_t st_mode; | ^~~~~~ ./usr/include/asm/stat.h:25:2: error: unknown type name 'uid_t' 25 | uid_t st_uid; | ^~~~~ ./usr/include/asm/stat.h:26:2: error: unknown type name 'gid_t' 26 | gid_t st_gid; | ^~~~~ ./usr/include/asm/stat.h:58:2: error: unknown type name 'mode_t' 58 | mode_t st_mode; | ^~~~~~ ./usr/include/asm/stat.h:61:2: error: unknown type name 'uid_t' 61 | uid_t st_uid; | ^~~~~ ./usr/include/asm/stat.h:62:2: error: unknown type name 'gid_t' 62 | gid_t st_gid; | ^~~~~ The errors can be fixed by prefixing the types with __kernel_. Then, remove the no-header-test entry from user/include/Makefile. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Christoph Hellwig <hch@lst.de>
2022-05-05termbits: Convert octal defines to hexIlpo Järvinen1-111/+111
Many archs have termbits.h as octal numbers. It makes hard for humans to parse the magnitude of large numbers correctly and to compare with hex ones of the same define. Convert octal values to hex. First step is an automated conversion with: for i in $(git ls-files | grep 'termbits\.h'); do awk --non-decimal-data '/^#define\s+[A-Z][A-Z0-9]*\s+0[0-9]/ { l=int(((length($3) - 1) * 3 + 3) / 4); repl = sprintf("0x%0" l "x", $3); print gensub(/[^[:blank:]]+/, repl, 3); next} {print}' $i > $i~; mv $i~ $i; done On top of that, some manual processing on alignment and number of zeros. In addition, small tweaks to formatting of a few comments on the same lines. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lore.kernel.org/r/2c8c96f-a12f-aadc-18ac-34c1d371929c@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-28net: SO_RCVMARK socket option for SO_MARK with recvmsg()Erin MacNeil1-0/+2
Adding a new socket option, SO_RCVMARK, to indicate that SO_MARK should be included in the ancillary data returned by recvmsg(). Renamed the sock_recv_ts_and_drops() function to sock_recv_cmsgs(). Signed-off-by: Erin MacNeil <lnx.erin@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Acked-by: Marc Kleine-Budde <mkl@pengutronix.de> Link: https://lore.kernel.org/r/20220427200259.2564-1-lnx.erin@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-26uapi: always define F_GETLK64/F_SETLK64/F_SETLKW64 in fcntl.hChristoph Hellwig1-2/+2
The F_GETLK64/F_SETLK64/F_SETLKW64 fcntl opcodes are only implemented for the 32-bit syscall APIs, but are also needed for compat handling on 64-bit kernels. Consolidate them in unistd.h instead of definining the internal compat definitions in compat.h, which is rather error prone (e.g. parisc gets the values wrong currently). Note that before this change they were never visible to userspace due to the fact that CONFIG_64BIT is only set for kernel builds. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/r/20220405071314.3225832-3-guoren@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-04-26uapi: simplify __ARCH_FLOCK{,64}_PAD a littleChristoph Hellwig1-23/+3
Don't bother to define the symbols empty, just don't use them. That makes the intent a little more clear. Remove the unused HAVE_ARCH_STRUCT_FLOCK64 define and merge the 32-bit mips struct flock into the generic one. Add a new __ARCH_FLOCK_EXTRA_SYSID macro following the style of __ARCH_FLOCK_PAD to avoid having a separate definition just for one architecture. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Guo Ren <guoren@kernel.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Heiko Stuebner <heiko@sntech.de> Link: https://lore.kernel.org/r/20220405071314.3225832-2-guoren@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-03-24mm: madvise: MADV_DONTNEED_LOCKEDJohannes Weiner1-0/+2
MADV_DONTNEED historically rejects mlocked ranges, but with MLOCK_ONFAULT and MCL_ONFAULT allowing to mlock without populating, there are valid use cases for depopulating locked ranges as well. Users mlock memory to protect secrets. There are allocators for secure buffers that want in-use memory generally mlocked, but cleared and invalidated memory to give up the physical pages. This could be done with explicit munlock -> mlock calls on free -> alloc of course, but that adds two unnecessary syscalls, heavy mmap_sem write locks, vma splits and re-merges - only to get rid of the backing pages. Users also mlockall(MCL_ONFAULT) to suppress sustained paging, but are okay with on-demand initial population. It seems valid to selectively free some memory during the lifetime of such a process, without having to mess with its overall policy. Why add a separate flag? Isn't this a pretty niche usecase? - MADV_DONTNEED has been bailing on locked vmas forever. It's at least conceivable that someone, somewhere is relying on mlock to protect data from perhaps broader invalidation calls. Changing this behavior now could lead to quiet data corruption. - It also clarifies expectations around MADV_FREE and maybe MADV_REMOVE. It avoids the situation where one quietly behaves different than the others. MADV_FREE_LOCKED can be added later. - The combination of mlock() and madvise() in the first place is probably niche. But where it happens, I'd say that dropping pages from a locked region once they don't contain secrets or won't page