bpf: Disable migration before calling ops->map_free()

The freeing of all map elements may invoke bpf_obj_free_fields() to free
the special fields in the map value. Since these special fields may be

bpf: Disable migration before calling ops->map_free()

The freeing of all map elements may invoke bpf_obj_free_fields() to free
the special fields in the map value. Since these special fields may be
allocated from bpf memory allocator, migrate_{disable|enable} pairs are
necessary for the freeing of these special fields.

To simplify reasoning about when migrate_disable() is needed for the
freeing of these special fields, let the caller to guarantee migration
is disabled before invoking bpf_obj_free_fields(). Therefore, disabling
migration before calling ops->map_free() to simplify the freeing of map
values or special fields allocated from bpf memory allocator.

After disabling migration in bpf_map_free(), there is no need for
additional migration_{disable|enable} pairs in these ->map_free()
callbacks. Remove these redundant invocations.

The migrate_{disable|enable} pairs in the underlying implementation of
bpf_obj_free_fields() will be removed by the following patch.

Signed-off-by: Hou Tao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

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bpf: Add necessary migrate_disable to range_tree.

When running bpf selftest (./test_progs -j), the following warnings
showed up:

$ ./test_progs -t arena_atomics
...
BUG: using smp_processor_i

bpf: Add necessary migrate_disable to range_tree.

When running bpf selftest (./test_progs -j), the following warnings
showed up:

$ ./test_progs -t arena_atomics
...
BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u19:0/12501
caller is bpf_mem_free+0x128/0x330
...
Call Trace:
<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_free
range_tree_destroy
arena_map_free
bpf_map_free_deferred
process_scheduled_works
...

For selftests arena_htab and arena_list, similar smp_process_id() BUGs are
dumped, and the following are two stack trace:

<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_alloc
range_tree_set
arena_map_alloc
map_create
...

<TASK>
dump_stack_lvl
check_preemption_disabled
bpf_mem_alloc
range_tree_clear
arena_vm_fault
do_pte_missing
handle_mm_fault
do_user_addr_fault
...

Add migrate_{disable,enable}() around related bpf_mem_{alloc,free}()
calls to fix the issue.

Fixes: b795379757eb ("bpf: Introduce range_tree data structure and use it in bpf arena")
Signed-off-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

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bpf: Introduce range_tree data structure and use it in bpf arena

Introduce range_tree data structure and use it in bpf arena to track
ranges of allocated pages. range_tree is a large bitmap that is

bpf: Introduce range_tree data structure and use it in bpf arena

Introduce range_tree data structure and use it in bpf arena to track
ranges of allocated pages. range_tree is a large bitmap that is
implemented as interval tree plus rbtree. The contiguous sequence of
bits represents unallocated pages.

Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Kumar Kartikeya Dwivedi <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

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