kernel/linux.git/fs/coredump.c, branch v6.18.22

coredump: fix core_pattern input validation

2025-10-07T11:12:46+00:00

In be1e0283021e ("coredump: don't pointlessly check and spew warnings") we tried to fix input validation so it only happens during a write to core_pattern. This would avoid needlessly logging a lot of warnings during a read operation. However the logic accidently got inverted in this commit. Fix it so the input validation only happens on write and is skipped on read. Fixes: be1e0283021e ("coredump: don't pointlessly check and spew warnings") Fixes: 16195d2c7dd2 ("coredump: validate socket name as it is written") Reviewed-by: Jan Kara Reported-by: Yu Watanabe Signed-off-by: Christian Brauner

Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:18:33+00:00

Pull MM updates from Andrew Morton: - "mm, swap: improve cluster scan strategy" from Kairui Song improves performance and reduces the failure rate of swap cluster allocation - "support large align and nid in Rust allocators" from Vitaly Wool permits Rust allocators to set NUMA node and large alignment when perforning slub and vmalloc reallocs - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend DAMOS_STAT's handling of the DAMON operations sets for virtual address spaces for ops-level DAMOS filters - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren Baghdasaryan reduces mmap_lock contention during reads of /proc/pid/maps - "mm/mincore: minor clean up for swap cache checking" from Kairui Song performs some cleanup in the swap code - "mm: vm_normal_page*() improvements" from David Hildenbrand provides code cleanup in the pagemap code - "add persistent huge zero folio support" from Pankaj Raghav provides a block layer speedup by optionalls making the huge_zero_pagepersistent, instead of releasing it when its refcount falls to zero - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to the recently added Kexec Handover feature - "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo Stoakes turns mm_struct.flags into a bitmap. To end the constant struggle with space shortage on 32-bit conflicting with 64-bit's needs - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap code - "selftests/mm: Fix false positives and skip unsupported tests" from Donet Tom fixes a few things in our selftests code - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised" from David Hildenbrand "allows individual processes to opt-out of THP=always into THP=madvise, without affecting other workloads on the system". It's a long story - the [1/N] changelog spells out the considerations - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on the memdesc project. Please see https://kernelnewbies.org/MatthewWilcox/Memdescs and https://blogs.oracle.com/linux/post/introducing-memdesc - "Tiny optimization for large read operations" from Chi Zhiling improves the efficiency of the pagecache read path - "Better split_huge_page_test result check" from Zi Yan improves our folio splitting selftest code - "test that rmap behaves as expected" from Wei Yang adds some rmap selftests - "remove write_cache_pages()" from Christoph Hellwig removes that function and converts its two remaining callers - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD selftests issues - "introduce kernel file mapped folios" from Boris Burkov introduces the concept of "kernel file pages". Using these permits btrfs to account its metadata pages to the root cgroup, rather than to the cgroups of random inappropriate tasks - "mm/pageblock: improve readability of some pageblock handling" from Wei Yang provides some readability improvements to the page allocator code - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON to understand arm32 highmem - "tools: testing: Use existing atomic.h for vma/maple tests" from Brendan Jackman performs some code cleanups and deduplication under tools/testing/ - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes a couple of 32-bit issues in tools/testing/radix-tree.c - "kasan: unify kasan_enabled() and remove arch-specific implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific initialization code into a common arch-neutral implementation - "mm: remove zpool" from Johannes Weiner removes zspool - an indirection layer which now only redirects to a single thing (zsmalloc) - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a couple of cleanups in the fork code - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of adjustments at various nth_page() callsites, eventually permitting the removal of that undesirable helper function - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun creates a KASAN read-only mode for ARM, using that architecture's memory tagging feature. It is felt that a read-only mode KASAN is suitable for use in production systems rather than debug-only - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does some tidying in the hugetlb folio allocation code - "mm: establish const-correctness for pointer parameters" from Max Kellermann makes quite a number of the MM API functions more accurate about the constness of their arguments. This was getting in the way of subsystems (in this case CEPH) when they attempt to improving their own const/non-const accuracy - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of code sites which were confused over when to use free_pages() vs __free_pages() - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the mapletree code accessible to Rust. Required by nouveau and by its forthcoming successor: the new Rust Nova driver - "selftests/mm: split_huge_page_test: split_pte_mapped_thp improvements" from David Hildenbrand adds a fix and some cleanups to the thp selftesting code - "mm, swap: introduce swap table as swap cache (phase I)" from Chris Li and Kairui Song is the first step along the path to implementing "swap tables" - a new approach to swap allocation and state tracking which is expected to yield speed and space improvements. This patchset itself yields a 5-20% performance benefit in some situations - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc layer to clean up the ptdesc code a little - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some issues in our 5-level pagetable selftesting code - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan addresses a couple of minor issues in relatively new memory allocation profiling feature - "Small cleanups" from Matthew Wilcox has a few cleanups in preparation for more memdesc work - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from Quanmin Yan makes some changes to DAMON in furtherance of supporting arm highmem - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad Anjum adds that compiler check to selftests code and fixes the fallout, by removing dead code - "Improvements to Victim Process Thawing and OOM Reaper Traversal Order" from zhongjinji makes a number of improvements in the OOM killer: mainly thawing a more appropriate group of victim threads so they can release resources - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park is a bunch of small and unrelated fixups for DAMON - "mm/damon: define and use DAMON initialization check function" from SeongJae Park implement reliability and maintainability improvements to a recently-added bug fix - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from SeongJae Park provides additional transparency to userspace clients of the DAMON_STAT information - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes some constraints on khubepaged's collapsing of anon VMAs. It also increases the success rate of MADV_COLLAPSE against an anon vma - "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()" from Lorenzo Stoakes moves us further towards removal of file_operations.mmap(). This patchset concentrates upon clearing up the treatment of stacked filesystems - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau provides some fixes and improvements to mlock's tracking of large folios. /proc/meminfo's "Mlocked" field became more accurate - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from Donet Tom fixes several user-visible KSM stats inaccuracies across forks and adds selftest code to verify these counters - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses some potential but presently benign issues in KSM's mm_slot handling * tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits) mm: swap: check for stable address space before operating on the VMA mm: convert folio_page() back to a macro mm/khugepaged: use start_addr/addr for improved readability hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list alloc_tag: fix boot failure due to NULL pointer dereference mm: silence data-race in update_hiwater_rss mm/memory-failure: don't select MEMORY_ISOLATION mm/khugepaged: remove definition of struct khugepaged_mm_slot mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL hugetlb: increase number of reserving hugepages via cmdline selftests/mm: add fork inheritance test for ksm_merging_pages counter mm/ksm: fix incorrect KSM counter handling in mm_struct during fork drivers/base/node: fix double free in register_one_node() mm: remove PMD alignment constraint in execmem_vmalloc() mm/memory_hotplug: fix typo 'esecially' -> 'especially' mm/rmap: improve mlock tracking for large folios mm/filemap: map entire large folio faultaround mm/fault: try to map the entire file folio in finish_fault() mm/rmap: mlock large folios in try_to_unmap_one() mm/rmap: fix a mlock race condition in folio_referenced_one() ...

Merge tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T17:27:17+00:00

Pull vfs workqueue updates from Christian Brauner: "This contains various workqueue changes affecting the filesystem layer. Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This replaces the use of system_wq and system_unbound_wq. system_wq is a per-CPU workqueue which isn't very obvious from the name and system_unbound_wq is to be used when locality is not required. So this renames system_wq to system_percpu_wq, and system_unbound_wq to system_dfl_wq. This also adds a new WQ_PERCPU flag to allow the fs subsystem users to explicitly request the use of per-CPU behavior. Both WQ_UNBOUND and WQ_PERCPU flags coexist for one release cycle to allow callers to transition their calls. WQ_UNBOUND will be removed in a next release cycle" * tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs: WQ_PERCPU added to alloc_workqueue users fs: replace use of system_wq with system_percpu_wq fs: replace use of system_unbound_wq with system_dfl_wq

fs: replace use of system_unbound_wq with system_dfl_wq

2025-09-19T14:15:07+00:00

Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. system_unbound_wq should be the default workqueue so as not to enforce locality constraints for random work whenever it's not required. Adding system_dfl_wq to encourage its use when unbound work should be used. The old system_unbound_wq will be kept for a few release cycles. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Link: https://lore.kernel.org/20250916082906.77439-2-marco.crivellari@suse.com Signed-off-by: Christian Brauner

mm: update coredump logic to correctly use bitmap mm flags

2025-09-13T23:54:57+00:00

The coredump logic is slightly different from other users in that it both stores mm flags and additionally sets and gets using masks. Since the MMF_DUMPABLE_* flags must remain as they are for uABI reasons, and of course these are within the first 32-bits of the flags, it is reasonable to provide access to these in the same fashion so this logic can all still keep working as it has been. Therefore, introduce coredump-specific helpers __mm_flags_get_dumpable() and __mm_flags_set_mask_dumpable() for this purpose, and update all core dump users of mm flags to use these. [lorenzo.stoakes@oracle.com: abstract set_mask_bits() invocation to mm_types.h to satisfy ARC] Link: https://lkml.kernel.org/r/0e7ad263-1ff7-446d-81fe-97cff9c0e7ed@lucifer.local Link: https://lkml.kernel.org/r/2a5075f7e3c5b367d988178c79a3063d12ee53a9.1755012943.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Reviewed-by: Mike Rapoport (Microsoft) Reviewed-by: Christian Brauner Acked-by: David Hildenbrand Cc: Adrian Hunter Cc: Alexander Gordeev Cc: Alexander Shishkin Cc: Al Viro Cc: Andreas Larsson Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Baolin Wang Cc: Barry Song Cc: Ben Segall Cc: Borislav Betkov Cc: Chengming Zhou Cc: Christian Borntraeger Cc: David Rientjes Cc: David S. Miller Cc: Dev Jain Cc: Dietmar Eggemann Cc: Gerald Schaefer Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ian Rogers Cc: Ingo Molnar Cc: Jan Kara Cc: Jann Horn Cc: Jason Gunthorpe Cc: Jiri Olsa Cc: John Hubbard Cc: Juri Lelli Cc: Kan Liang Cc: Kees Cook Cc: Marc Rutland Cc: Mariano Pache Cc: "Masami Hiramatsu (Google)" Cc: Mateusz Guzik Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Michal Hocko Cc: Namhyung kim Cc: Oleg Nesterov Cc: Peter Xu Cc: Peter Zijlstra Cc: Ryan Roberts Cc: Shakeel Butt Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Gleinxer Cc: Valentin Schneider Cc: Vasily Gorbik Cc: Vincent Guittot Cc: Vlastimil Babka Cc: xu xin Cc: Zi Yan Signed-off-by: Andrew Morton

coredump: don't pointlessly check and spew warnings

2025-08-21T11:54:40+00:00

When a write happens it doesn't make sense to check perform checks on the input. Skip them. Whether a fixes tag is licensed is a bit of a gray area here but I'll add one for the socket validation part I added recently. Link: https://lore.kernel.org/20250821-moosbedeckt-denunziant-7908663f3563@brauner Fixes: 16195d2c7dd2 ("coredump: validate socket name as it is written") Reported-by: Brad Spengler Signed-off-by: Christian Brauner

coredump: Fix return value in coredump_parse()

2025-08-19T11:51:28+00:00

The coredump_parse() function is bool type. It should return true on success and false on failure. The cn_printf() returns zero on success or negative error codes. This mismatch means that when "return err;" here, it is treated as success instead of failure. Change it to return false instead. Fixes: a5715af549b2 ("coredump: make coredump_parse() return bool") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/aKRGu14w5vPSZLgv@stanley.mountain Signed-off-by: Christian Brauner

Merge tag 'vfs-6.17-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-07-28T21:10:15+00:00

Pull pidfs updates from Christian Brauner: - persistent info Persist exit and coredump information independent of whether anyone currently holds a pidfd for the struct pid. The current scheme allocated pidfs dentries on-demand repeatedly. This scheme is reaching it's limits as it makes it impossible to pin information that needs to be available after the task has exited or coredumped and that should not be lost simply because the pidfd got closed temporarily. The next opener should still see the stashed information. This is also a prerequisite for supporting extended attributes on pidfds to allow attaching meta information to them. If someone opens a pidfd for a struct pid a pidfs dentry is allocated and stashed in pid->stashed. Once the last pidfd for the struct pid is closed the pidfs dentry is released and removed from pid->stashed. So if 10 callers create a pidfs dentry for the same struct pid sequentially, i.e., each closing the pidfd before the other creates a new one then a new pidfs dentry is allocated every time. Because multiple tasks acquiring and releasing a pidfd for the same struct pid can race with each another a task may still find a valid pidfs entry from the previous task in pid->stashed and reuse it. Or it might find a dead dentry in there and fail to reuse it and so stashes a new pidfs dentry. Multiple tasks may race to stash a new pidfs dentry but only one will succeed, the other ones will put their dentry. The current scheme aims to ensure that a pidfs dentry for a struct pid can only be created if the task is still alive or if a pidfs dentry already existed before the task was reaped and so exit information has been was stashed in the pidfs inode. That's great except that it's buggy. If a pidfs dentry is stashed in pid->stashed after pidfs_exit() but before __unhash_process() is called we will return a pidfd for a reaped task without exit information being available. The pidfds_pid_valid() check does not guard against this race as it doens't sync at all with pidfs_exit(). The pid_has_task() check might be successful simply because we're before __unhash_process() but after pidfs_exit(). Introduce a new scheme where the lifetime of information associated with a pidfs entry (coredump and exit information) isn't bound to the lifetime of the pidfs inode but the struct pid itself. The first time a pidfs dentry is allocated for a struct pid a struct pidfs_attr will be allocated which will be used to store exit and coredump information. If all pidfs for the pidfs dentry are closed the dentry and inode can be cleaned up but the struct pidfs_attr will stick until the struct pid itself is freed. This will ensure minimal memory usage while persisting relevant information. The new scheme has various advantages. First, it allows to close the race where we end up handing out a pidfd for a reaped task for which no exit information is available. Second, it minimizes memory usage. Third, it allows to remove complex lifetime tracking via dentries when registering a struct pid with pidfs. There's no need to get or put a reference. Instead, the lifetime of exit and coredump information associated with a struct pid is bound to the lifetime of struct pid itself. - extended attributes Now that we have a way to persist information for pidfs dentries we can start supporting extended attributes on pidfds. This will allow userspace to attach meta information to tasks. One natural extension would be to introduce a custom pidfs.* extended attribute space and allow for the inheritance of extended attributes across fork() and exec(). The first simple scheme will allow privileged userspace to set trusted extended attributes on pidfs inodes. - Allow autonomous pidfs file handles Various filesystems such as pidfs and drm support opening file handles without having to require a file descriptor to identify the filesystem. The filesystem are global single instances and can be trivially identified solely on the information encoded in the file handle. This makes it possible to not have to keep or acquire a sentinal file descriptor just to pass it to open_by_handle_at() to identify the filesystem. That's especially useful when such sentinel file descriptor cannot or should not be acquired. For pidfs this means a file handle can function as full replacement for storing a pid in a file. Instead a file handle can be stored and reopened purely based on the file handle. Such autonomous file handles can be opened with or without specifying a a file descriptor. If no proper file descriptor is used the FD_PIDFS_ROOT sentinel must be passed. This allows us to define further special negative fd sentinels in the future. Userspace can trivially test for support by trying to open the file handle with an invalid file descriptor. - Allow pidfds for reaped tasks with SCM_PIDFD messages This is a logical continuation of the earlier work to create pidfds for reaped tasks through the SO_PEERPIDFD socket option merged in 923ea4d4482b ("Merge patch series "net, pidfs: enable handing out pidfds for reaped sk->sk_peer_pid""). - Two minor fixes: * Fold fs_struct->{lock,seq} into a seqlock * Don't bother with path_{get,put}() in unix_open_file() * tag 'vfs-6.17-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (37 commits) don't bother with path_get()/path_put() in unix_open_file() fold fs_struct->{lock,seq} into a seqlock selftests: net: extend SCM_PIDFD test to cover stale pidfds af_unix: enable handing out pidfds for reaped tasks in SCM_PIDFD af_unix: stash pidfs dentry when needed af_unix/scm: fix whitespace errors af_unix: introduce and use scm_replace_pid() helper af_unix: introduce unix_skb_to_scm helper af_unix: rework unix_maybe_add_creds() to allow sleep selftests/pidfd: decode pidfd file handles withou having to specify an fd fhandle, pidfs: support open_by_handle_at() purely based on file handle uapi/fcntl: add FD_PIDFS_ROOT uapi/fcntl: add FD_INVALID fcntl/pidfd: redefine PIDFD_SELF_THREAD_GROUP uapi/fcntl: mark range as reserved fhandle: reflow get_path_anchor() pidfs: add pidfs_root_path() helper fhandle: rename to get_path_anchor() fhandle: hoist copy_from_user() above get_path_from_fd() fhandle: raise FILEID_IS_DIR in handle_type ...

coredump: add coredump_skip() helper

2025-07-07T10:24:51+00:00

Link: https://lore.kernel.org/20250612-work-coredump-massage-v1-24-315c0c34ba94@kernel.org Signed-off-by: Christian Brauner

coredump: avoid pointless variable

2025-07-07T10:24:51+00:00

we don't use that value at all so don't bother with it in the first place. Link: https://lore.kernel.org/20250612-work-coredump-massage-v1-23-315c0c34ba94@kernel.org Signed-off-by: Christian Brauner