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mm/page_alloc: skip debug_check_no_{obj,locks}_freed with FPI_TRYLOCK

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[ Upstream commit 338ad1e84d ]

When CONFIG_DEBUG_OBJECTS_FREE is enabled,
debug_check_no_{obj,locks}_freed() functions are called.

Since both of them spin on a lock, they are not safe to be called if the
FPI_TRYLOCK flag is specified.  This leads to a lockdep splat:

  ================================
  WARNING: inconsistent lock state
  6.19.0-rc5-slab-for-next+ #326 Tainted: G                 N
  --------------------------------
  inconsistent {INITIAL USE} -> {IN-NMI} usage.
  kunit_try_catch/9046 [HC2[2]:SC0[0]:HE0:SE1] takes:
  ffffffff84ed6bf8 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_check_no_obj_freed+0xe0/0x300
  {INITIAL USE} state was registered at:
    lock_acquire+0xd9/0x2f0
    _raw_spin_lock_irqsave+0x4c/0x80
    __debug_object_init+0x9d/0x1f0
    debug_object_init+0x34/0x50
    __init_work+0x28/0x40
    init_cgroup_housekeeping+0x151/0x210
    init_cgroup_root+0x3d/0x140
    cgroup_init_early+0x30/0x240
    start_kernel+0x3e/0xcd0
    x86_64_start_reservations+0x18/0x30
    x86_64_start_kernel+0xf3/0x140
    common_startup_64+0x13e/0x148
  irq event stamp: 2998
  hardirqs last  enabled at (2997): [<ffffffff8298b77a>] exc_nmi+0x11a/0x240
  hardirqs last disabled at (2998): [<ffffffff8298b991>] sysvec_irq_work+0x11/0x110
  softirqs last  enabled at (1416): [<ffffffff813c1f72>] __irq_exit_rcu+0x132/0x1c0
  softirqs last disabled at (1303): [<ffffffff813c1f72>] __irq_exit_rcu+0x132/0x1c0

  other info that might help us debug this:
   Possible unsafe locking scenario:

         CPU0
         ----
    lock(&obj_hash[i].lock);
    <Interrupt>
      lock(&obj_hash[i].lock);

   *** DEADLOCK ***

Rename free_pages_prepare() to __free_pages_prepare(), add an fpi_t
parameter, and skip those checks if FPI_TRYLOCK is set.  To keep the fpi_t
definition in mm/page_alloc.c, add a wrapper function free_pages_prepare()
that always passes FPI_NONE and use it in mm/compaction.c.

Link: https://lkml.kernel.org/r/20260209062639.16577-1-harry.yoo@oracle.com
Fixes: 8c57b687e8 ("mm, bpf: Introduce free_pages_nolock()")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Harry Yoo 2026-02-09 15:26:39 +09:00 • committed by Sasha Levin
commit f64491066c
1 changed files with 11 additions and 6 deletions
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