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    Subject[PATCH 5.16 0204/1039] rcu: Avoid alloc_pages() when recording stack
    Date
    From: Jun Miao <jun.miao@intel.com>

    [ Upstream commit 300c0c5e721834f484b03fa3062602dd8ff48413 ]

    The default kasan_record_aux_stack() calls stack_depot_save() with GFP_NOWAIT,
    which in turn can then call alloc_pages(GFP_NOWAIT, ...). In general, however,
    it is not even possible to use either GFP_ATOMIC nor GFP_NOWAIT in certain
    non-preemptive contexts/RT kernel including raw_spin_locks (see gfp.h and ab00db216c9c7).
    Fix it by instructing stackdepot to not expand stack storage via alloc_pages()
    in case it runs out by using kasan_record_aux_stack_noalloc().

    Jianwei Hu reported:
    BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
    in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 15319, name: python3
    INFO: lockdep is turned off.
    irq event stamp: 0
    hardirqs last enabled at (0): [<0000000000000000>] 0x0
    hardirqs last disabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
    softirqs last enabled at (0): [<ffffffff856c8b13>] copy_process+0xaf3/0x2590
    softirqs last disabled at (0): [<0000000000000000>] 0x0
    CPU: 6 PID: 15319 Comm: python3 Tainted: G W O 5.15-rc7-preempt-rt #1
    Hardware name: Supermicro SYS-E300-9A-8C/A2SDi-8C-HLN4F, BIOS 1.1b 12/17/2018
    Call Trace:
    show_stack+0x52/0x58
    dump_stack+0xa1/0xd6
    ___might_sleep.cold+0x11c/0x12d
    rt_spin_lock+0x3f/0xc0
    rmqueue+0x100/0x1460
    rmqueue+0x100/0x1460
    mark_usage+0x1a0/0x1a0
    ftrace_graph_ret_addr+0x2a/0xb0
    rmqueue_pcplist.constprop.0+0x6a0/0x6a0
    __kasan_check_read+0x11/0x20
    __zone_watermark_ok+0x114/0x270
    get_page_from_freelist+0x148/0x630
    is_module_text_address+0x32/0xa0
    __alloc_pages_nodemask+0x2f6/0x790
    __alloc_pages_slowpath.constprop.0+0x12d0/0x12d0
    create_prof_cpu_mask+0x30/0x30
    alloc_pages_current+0xb1/0x150
    stack_depot_save+0x39f/0x490
    kasan_save_stack+0x42/0x50
    kasan_save_stack+0x23/0x50
    kasan_record_aux_stack+0xa9/0xc0
    __call_rcu+0xff/0x9c0
    call_rcu+0xe/0x10
    put_object+0x53/0x70
    __delete_object+0x7b/0x90
    kmemleak_free+0x46/0x70
    slab_free_freelist_hook+0xb4/0x160
    kfree+0xe5/0x420
    kfree_const+0x17/0x30
    kobject_cleanup+0xaa/0x230
    kobject_put+0x76/0x90
    netdev_queue_update_kobjects+0x17d/0x1f0
    ... ...
    ksys_write+0xd9/0x180
    __x64_sys_write+0x42/0x50
    do_syscall_64+0x38/0x50
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

    Links: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/linux/kasan.h?id=7cb3007ce2da27ec02a1a3211941e7fe6875b642
    Fixes: 84109ab58590 ("rcu: Record kvfree_call_rcu() call stack for KASAN")
    Fixes: 26e760c9a7c8 ("rcu: kasan: record and print call_rcu() call stack")
    Reported-by: Jianwei Hu <jianwei.hu@windriver.com>
    Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
    Acked-by: Marco Elver <elver@google.com>
    Tested-by: Juri Lelli <juri.lelli@redhat.com>
    Signed-off-by: Jun Miao <jun.miao@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/rcu/tree.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
    index ef8d36f580fc3..906b6887622d3 100644
    --- a/kernel/rcu/tree.c
    +++ b/kernel/rcu/tree.c
    @@ -2982,7 +2982,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
    head->func = func;
    head->next = NULL;
    local_irq_save(flags);
    - kasan_record_aux_stack(head);
    + kasan_record_aux_stack_noalloc(head);
    rdp = this_cpu_ptr(&rcu_data);

    /* Add the callback to our list. */
    @@ -3547,7 +3547,7 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
    return;
    }

    - kasan_record_aux_stack(ptr);
    + kasan_record_aux_stack_noalloc(ptr);
    success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
    if (!success) {
    run_page_cache_worker(krcp);
    --
    2.34.1


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