linux.git/kernel, branch dev

task_work: make TWA_NMI_CURRENT handling conditional on IRQ_WORK

2024-07-29T19:05:06+00:00

The TWA_NMI_CURRENT handling very much depends on IRQ_WORK, but that isn't universally enabled everywhere. Maybe the IRQ_WORK infrastructure should just be unconditional - x86 ends up indirectly enabling it through unconditionally enabling PERF_EVENTS, for example. But it also gets enabled by having SMP support, or even if you just have PRINTK enabled. But in the meantime TWA_NMI_CURRENT causes tons of build failures on various odd minimal configs. Which did show up in linux-next, but despite that nobody bothered to fix it or even inform me until -rc1 was out. Fixes: 466e4d801cd4 ("task_work: Add TWA_NMI_CURRENT as an additional notify mode") Reported-by: Naresh Kamboju Reported-by: kernelci.org bot Reported-by: Guenter Roeck Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Signed-off-by: Linus Torvalds

profiling: attempt to remove per-cpu profile flip buffer

2024-07-29T17:58:28+00:00

This is the really old legacy kernel profiling code, which has long since been obviated by "real profiling" (ie 'prof' and company), and mainly remains as a source of syzbot reports. There are anecdotal reports that people still use it for boot-time profiling, but it's unlikely that such use would care about the old NUMA optimizations in this code from 2004 (commit ad02973d42: "profile: 512x Altix timer interrupt livelock fix" in the BK import archive at [1]) So in order to head off future syzbot reports, let's try to simplify this code and get rid of the per-cpu profile buffers that are quite a large portion of the complexity footprint of this thing (including CPU hotplug callbacks etc). It's unlikely anybody will actually notice, or possibly, as Thomas put it: "Only people who indulge in nostalgia will notice :)". That said, if it turns out that this code is actually actively used by somebody, we can always revert this removal. Thus the "attempt" in the summary line. [ Note: in a small nod to "the profiling code can cause NUMA problems", this also removes the "increment the last entry in the profiling array on any unknown hits" logic. That would account any program counter in a module to that single counter location, and might exacerbate any NUMA cacheline bouncing issues ] Link: https://lore.kernel.org/all/CAHk-=wgs52BxT4Zjmjz8aNvHWKxf5_ThBY4bYL1Y6CTaNL2dTw@mail.gmail.com/ Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git [1] Cc: Thomas Gleixner Cc: Tetsuo Handa Signed-off-by: Linus Torvalds

profiling: remove prof_cpu_mask

2024-07-29T17:45:54+00:00

syzbot is reporting uninit-value at profile_hits(), for there is a race window between if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL)) return -ENOMEM; cpumask_copy(prof_cpu_mask, cpu_possible_mask); in profile_init() and cpumask_available(prof_cpu_mask) && cpumask_test_cpu(smp_processor_id(), prof_cpu_mask)) in profile_tick(); prof_cpu_mask remains uninitialzed until cpumask_copy() completes while cpumask_available(prof_cpu_mask) returns true as soon as alloc_cpumask_var(&prof_cpu_mask) completes. We could replace alloc_cpumask_var() with zalloc_cpumask_var() and call cpumask_copy() from create_proc_profile() on only UP kernels, for profile_online_cpu() calls cpumask_set_cpu() as needed via cpuhp_setup_state(CPUHP_AP_ONLINE_DYN) on SMP kernels. But this patch removes prof_cpu_mask because it seems unnecessary. The cpumask_test_cpu(smp_processor_id(), prof_cpu_mask) test in profile_tick() is likely always true due to a CPU cannot call profile_tick() if that CPU is offline and cpumask_set_cpu(cpu, prof_cpu_mask) is called when that CPU becomes online and cpumask_clear_cpu(cpu, prof_cpu_mask) is called when that CPU becomes offline . This test could be false during transition between online and offline. But according to include/linux/cpuhotplug.h , CPUHP_PROFILE_PREPARE belongs to PREPARE section, which means that the CPU subjected to profile_dead_cpu() cannot be inside profile_tick() (i.e. no risk of use-after-free bug) because interrupt for that CPU is disabled during PREPARE section. Therefore, this test is guaranteed to be true, and can be removed. (Since profile_hits() checks prof_buffer != NULL, we don't need to check prof_buffer != NULL here unless get_irq_regs() or user_mode() is such slow that we want to avoid when prof_buffer == NULL). do_profile_hits() is called from profile_tick() from timer interrupt only if cpumask_test_cpu(smp_processor_id(), prof_cpu_mask) is true and prof_buffer is not NULL. But syzbot is also reporting that sometimes do_profile_hits() is called while current thread is still doing vzalloc(), where prof_buffer must be NULL at this moment. This indicates that multiple threads concurrently tried to write to /sys/kernel/profiling interface, which caused that somebody else try to re-allocate prof_buffer despite somebody has already allocated prof_buffer. Fix this by using serialization. Reported-by: syzbot Closes: https://syzkaller.appspot.com/bug?extid=b1a83ab2a9eb9321fbdd Signed-off-by: Tetsuo Handa Tested-by: syzbot Signed-off-by: Linus Torvalds

minmax: make generic MIN() and MAX() macros available everywhere

2024-07-28T22:49:18+00:00

This just standardizes the use of MIN() and MAX() macros, with the very traditional semantics. The goal is to use these for C constant expressions and for top-level / static initializers, and so be able to simplify the min()/max() macros. These macro names were used by various kernel code - they are very traditional, after all - and all such users have been fixed up, with a few different approaches: - trivial duplicated macro definitions have been removed Note that 'trivial' here means that it's obviously kernel code that already included all the major kernel headers, and thus gets the new generic MIN/MAX macros automatically. - non-trivial duplicated macro definitions are guarded with #ifndef This is the "yes, they define their own versions, but no, the include situation is not entirely obvious, and maybe they don't get the generic version automatically" case. - strange use case #1 A couple of drivers decided that the way they want to describe their versioning is with #define MAJ 1 #define MIN 2 #define DRV_VERSION __stringify(MAJ) "." __stringify(MIN) which adds zero value and I just did my Alexander the Great impersonation, and rewrote that pointless Gordian knot as #define DRV_VERSION "1.2" instead. - strange use case #2 A couple of drivers thought that it's a good idea to have a random 'MIN' or 'MAX' define for a value or index into a table, rather than the traditional macro that takes arguments. These values were re-written as C enum's instead. The new function-line macros only expand when followed by an open parenthesis, and thus don't clash with enum use. Happily, there weren't really all that many of these cases, and a lot of users already had the pattern of using '#ifndef' guarding (or in one case just using '#undef MIN') before defining their own private version that does the same thing. I left such cases alone. Cc: David Laight Cc: Lorenzo Stoakes Signed-off-by: Linus Torvalds

Merge tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-07-27T17:19:55+00:00

Pull timer migration updates from Thomas Gleixner: "Fixes and minor updates for the timer migration code: - Stop testing the group->parent pointer as it is not guaranteed to be stable over a chain of operations by design. This includes a warning which would be nice to have but it produces false positives due to the racy nature of the check. - Plug a race between CPUs going in and out of idle and a CPU hotplug operation. The latter can create and connect a new hierarchy level which is missed in the concurrent updates of CPUs which go into idle. As a result the events of such a CPU might not be processed and timers go stale. Cure it by splitting the hotplug operation into a prepare and online callback. The prepare callback is guaranteed to run on an online and therefore active CPU. This CPU updates the hierarchy and being online ensures that there is always at least one migrator active which handles the modified hierarchy correctly when going idle. The online callback which runs on the incoming CPU then just marks the CPU active and brings it into operation. - Improve tracing and polish the code further so it is more obvious what's going on" * tag 'timers-urgent-2024-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timers/migration: Fix grammar in comment timers/migration: Spare write when nothing changed timers/migration: Rename childmask by groupmask to make naming more obvious timers/migration: Read childmask and parent pointer in a single place timers/migration: Use a single struct for hierarchy walk data timers/migration: Improve tracing timers/migration: Move hierarchy setup into cpuhotplug prepare callback timers/migration: Do not rely always on group->parent

Merge tag 'net-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2024-07-25T20:32:25+00:00

Pull networking fixes from Jakub Kicinski: "Including fixes from bpf and netfilter. A lot of networking people were at a conference last week, busy catching COVID, so relatively short PR. Current release - regressions: - tcp: process the 3rd ACK with sk_socket for TFO and MPTCP Current release - new code bugs: - l2tp: protect session IDR and tunnel session list with one lock, make sure the state is coherent to avoid a warning - eth: bnxt_en: update xdp_rxq_info in queue restart logic - eth: airoha: fix location of the MBI_RX_AGE_SEL_MASK field Previous releases - regressions: - xsk: require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len, the field reuses previously un-validated pad Previous releases - always broken: - tap/tun: drop short frames to prevent crashes later in the stack - eth: ice: add a per-VF limit on number of FDIR filters - af_unix: disable MSG_OOB handling for sockets in sockmap/sockhash" * tag 'net-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (34 commits) tun: add missing verification for short frame tap: add missing verification for short frame mISDN: Fix a use after free in hfcmulti_tx() gve: Fix an edge case for TSO skb validity check bnxt_en: update xdp_rxq_info in queue restart logic tcp: process the 3rd ACK with sk_socket for TFO/MPTCP selftests/bpf: Add XDP_UMEM_TX_METADATA_LEN to XSK TX metadata test xsk: Require XDP_UMEM_TX_METADATA_LEN to actuate tx_metadata_len bpf: Fix a segment issue when downgrading gso_size net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling MAINTAINERS: make Breno the netconsole maintainer MAINTAINERS: Update bonding entry net: nexthop: Initialize all fields in dumped nexthops net: stmmac: Correct byte order of perfect_match selftests: forwarding: skip if kernel not support setting bridge fdb learning limit tipc: Return non-zero value from tipc_udp_addr2str() on error netfilter: nft_set_pipapo_avx2: disable softinterrupts ice: Fix recipe read procedure ice: Add a per-VF limit on number of FDIR filters net: bonding: correctly annotate RCU in bond_should_notify_peers() ...

Merge tag 'printk-for-6.11-trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2024-07-25T20:18:41+00:00

Pull printk updates from Petr Mladek: - trivial printk changes The bigger "real" printk work is still being discussed. * tag 'printk-for-6.11-trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: vsprintf: add missing MODULE_DESCRIPTION() macro printk: Rename console_replay_all() and update context

Merge tag 'constfy-sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

2024-07-25T19:58:36+00:00

Pull sysctl constification from Joel Granados: "Treewide constification of the ctl_table argument of proc_handlers using a coccinelle script and some manual code formatting fixups. This is a prerequisite to moving the static ctl_table structs into read-only data section which will ensure that proc_handler function pointers cannot be modified" * tag 'constfy-sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: sysctl: treewide: constify the ctl_table argument of proc_handlers

Merge tag 'kgdb-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux

2024-07-25T19:48:42+00:00

Pull kgdb updates from Daniel Thompson: "Three small changes this cycle: - Clean up an architecture abstraction that is no longer needed because all the architectures have converged. - Actually use the prompt argument to kdb_position_cursor() instead of ignoring it (functionally this fix is a nop but that was due to luck rather than good judgement) - Fix a -Wformat-security warning" * tag 'kgdb-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/danielt/linux: kdb: Get rid of redundant kdb_curr_task() kdb: Use the passed prompt in kdb_position_cursor() kdb: address -Wformat-security warnings

Merge tag 'dma-mapping-6.11-2024-07-24' of git://git.infradead.org/users/hch/dma-mapping

2024-07-25T17:10:34+00:00

Pull dma-mapping fix from Christoph Hellwig: - fix the order of actions in dmam_free_coherent (Lance Richardson) * tag 'dma-mapping-6.11-2024-07-24' of git://git.infradead.org/users/hch/dma-mapping: dma: fix call order in dmam_free_coherent