linux.git/kernel/bpf/task_iter.c, branch v6.6.132

bpf: Fix iter/task tid filtering

2024-11-01T00:58:25+00:00

[ Upstream commit 9495a5b731fcaf580448a3438d63601c88367661 ]

In userspace, you can add a tid filter by setting
the "task.tid" field for "bpf_iter_link_info".
However, `get_pid_task` when called for the
`BPF_TASK_ITER_TID` type should have been using
`PIDTYPE_PID` (tid) instead of `PIDTYPE_TGID` (pid).

Fixes: f0d74c4da1f0 ("bpf: Parameterize task iterators.")
Signed-off-by: Jordan Rome 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20241016210048.1213935-1-linux@jordanrome.com
Signed-off-by: Sasha Levin

bpf: keep a reference to the mm, in case the task is dead.

2022-12-28T22:11:48+00:00

Fix the system crash that happens when a task iterator travel through
vma of tasks.

In task iterators, we used to access mm by following the pointer on
the task_struct; however, the death of a task will clear the pointer,
even though we still hold the task_struct.  That can cause an
unexpected crash for a null pointer when an iterator is visiting a
task that dies during the visit.  Keeping a reference of mm on the
iterator ensures we always have a valid pointer to mm.

Co-developed-by: Song Liu 
Signed-off-by: Song Liu 
Signed-off-by: Kui-Feng Lee 
Reported-by: Nathan Slingerland 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/r/20221216221855.4122288-2-kuifeng@meta.com
Signed-off-by: Alexei Starovoitov

Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-11T00:53:04+00:00

Pull MM updates from Andrew Morton:

- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).

- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.

Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.

Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.

- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.

KMSAN keeps finding bugs. New ones, as well as the legacy ones.

- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.

- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.

- userfaultfd updates from Axel Rasmussen

- zsmalloc cleanups from Alexey Romanov

- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure

- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.

- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.

- memcg cleanups from Kairui Song.

- memcg fixes and cleanups from Johannes Weiner.

- Vishal Moola provides more folio conversions

- Zhang Yi removed ll_rw_block() :(

- migration enhancements from Peter Xu

- migration error-path bugfixes from Huang Ying

- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.

- vma merging improvements from Jakub Matěn.

- NUMA hinting cleanups from David Hildenbrand.

- xu xin added aditional userspace visibility into KSM merging
activity.

- THP & KSM code consolidation from Qi Zheng.

- more folio work from Matthew Wilcox.

- KASAN updates from Andrey Konovalov.

- DAMON cleanups from Kaixu Xia.

- DAMON work from SeongJae Park: fixes, cleanups.

- hugetlb sysfs cleanups from Muchun Song.

- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.

Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]

* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...

bpf: Handle show_fdinfo for the parameterized task BPF iterators

2022-09-28T23:30:00+00:00

Show information of iterators in the respective files under
/proc//fdinfo/.

For example, for a task file iterator with 1723 as the value of tid
parameter, its fdinfo would look like the following lines.

    pos:    0
    flags:  02000000
    mnt_id: 14
    ino:    38
    link_type:      iter
    link_id:        51
    prog_tag:       a590ac96db22b825
    prog_id:        299
    target_name:    task_file
    task_type:      TID
    tid: 1723

This patch add the last three fields.  task_type is the type of the
task parameter.  TID means the iterator visit only the thread
specified by tid.  The value of tid in the above example is 1723.  For
the case of PID task_type, it means the iterator visits only threads
of a process and will show the pid value of the process instead of a
tid.

Signed-off-by: Kui-Feng Lee 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20220926184957.208194-4-kuifeng@fb.com

bpf: Handle bpf_link_info for the parameterized task BPF iterators.

2022-09-28T23:29:55+00:00

Add new fields to bpf_link_info that users can query it through
bpf_obj_get_info_by_fd().

Signed-off-by: Kui-Feng Lee 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20220926184957.208194-3-kuifeng@fb.com

bpf: Parameterize task iterators.

2022-09-28T23:29:47+00:00

Allow creating an iterator that loops through resources of one
thread/process.

People could only create iterators to loop through all resources of
files, vma, and tasks in the system, even though they were interested
in only the resources of a specific task or process.  Passing the
additional parameters, people can now create an iterator to go
through all resources or only the resources of a task.

Signed-off-by: Kui-Feng Lee 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/20220926184957.208194-2-kuifeng@fb.com

bpf: remove VMA linked list

2022-09-27T02:46:22+00:00

Use vma_next() and remove reference to the start of the linked list

Link: https://lkml.kernel.org/r/20220906194824.2110408-51-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett 
Tested-by: Yu Zhao 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: "Matthew Wilcox (Oracle)" 
Cc: SeongJae Park 
Cc: Sven Schnelle 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

bpf: Remove redundant assignment to meta.seq in __task_seq_show()

2022-04-11T19:14:34+00:00

The seq argument is assigned to meta.seq twice, the second one is
redundant, remove it.

This patch also removes a redundant space in bpf_iter_link_attach().

Signed-off-by: Yuntao Wang 
Signed-off-by: Daniel Borkmann 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/20220410060020.307283-1-ytcoode@gmail.com

bpf: Introduce btf_tracing_ids

2021-11-12T18:19:09+00:00

Similar to btf_sock_ids, btf_tracing_ids provides btf ID for task_struct,
file, and vm_area_struct via easy to understand format like
btf_tracing_ids[BTF_TRACING_TYPE_[TASK|file|VMA]].

Suggested-by: Alexei Starovoitov 
Signed-off-by: Song Liu 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20211112150243.1270987-3-songliubraving@fb.com

bpf: Introduce helper bpf_find_vma

2021-11-07T19:54:51+00:00

In some profiler use cases, it is necessary to map an address to the
backing file, e.g., a shared library. bpf_find_vma helper provides a
flexible way to achieve this. bpf_find_vma maps an address of a task to
the vma (vm_area_struct) for this address, and feed the vma to an callback
BPF function. The callback function is necessary here, as we need to
ensure mmap_sem is unlocked.

It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem
safely when irqs are disable, we use the same mechanism as stackmap with
build_id. Specifically, when irqs are disabled, the unlocked is postponed
in an irq_work. Refactor stackmap.c so that the irq_work is shared among
bpf_find_vma and stackmap helpers.

Signed-off-by: Song Liu 
Signed-off-by: Alexei Starovoitov 
Tested-by: Hengqi Chen 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20211105232330.1936330-2-songliubraving@fb.com