| Message ID | 20210908224438.391816-1-yhs@fb.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [mm/bpf,v3] mm: bpf: add find_vma_non_owner() without lockdep_assert on mm->mmap_lock | expand |
On Wed, Sep 08, 2021 at 03:44:38PM -0700, Yonghong Song wrote: > +extern struct vm_area_struct * find_vma_non_owner(struct mm_struct * mm, > + unsigned long addr); - extern is deprecated - no space between the '*' and 'mm'. - no space between the '*' and the function name. > +struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) > +{ > + lockdep_assert_held(&mm->mmap_lock); > + return find_vma_non_owner(mm, addr); > +} > + > EXPORT_SYMBOL(find_vma); No blank line between the closing '}' and the EXPORT_SYMBOL.
On 9/8/21 6:38 PM, Matthew Wilcox wrote: > On Wed, Sep 08, 2021 at 03:44:38PM -0700, Yonghong Song wrote: >> +extern struct vm_area_struct * find_vma_non_owner(struct mm_struct * mm, >> + unsigned long addr); > > - extern is deprecated > - no space between the '*' and 'mm'. > - no space between the '*' and the function name. > >> +struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) >> +{ >> + lockdep_assert_held(&mm->mmap_lock); >> + return find_vma_non_owner(mm, addr); >> +} >> + >> EXPORT_SYMBOL(find_vma); > > No blank line between the closing '}' and the EXPORT_SYMBOL. Thanks for your comment. I just followed the original coding style for the above change. BTW, I will have a new version anyway so I won't touch the above code any more.
diff --git a/include/linux/mm.h b/include/linux/mm.h index 50e2c2914ac2..f5751b7f95b6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2672,6 +2672,8 @@ extern int expand_upwards(struct vm_area_struct *vma, unsigned long address); extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr); extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr, struct vm_area_struct **pprev); +extern struct vm_area_struct * find_vma_non_owner(struct mm_struct * mm, + unsigned long addr); /** * find_vma_intersection() - Look up the first VMA which intersects the interval diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index e8eefdf8cf3e..b899eb407654 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -190,7 +190,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } for (i = 0; i < trace_nr; i++) { - vma = find_vma(current->mm, ips[i]); + vma = find_vma_non_owner(current->mm, ips[i]); if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { /* per entry fall back to ips */ id_offs[i].status = BPF_STACK_BUILD_ID_IP; diff --git a/mm/mmap.c b/mm/mmap.c index 88dcc5c25225..6c1e91ac36f7 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2270,12 +2270,12 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, EXPORT_SYMBOL(get_unmapped_area); /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ -struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) +struct vm_area_struct *find_vma_non_owner(struct mm_struct *mm, unsigned long addr) { struct rb_node *rb_node; struct vm_area_struct *vma; - mmap_assert_locked(mm); + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm); /* Check the cache first. */ vma = vmacache_find(mm, addr); if (likely(vma)) @@ -2302,6 +2302,12 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) return vma; } +struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) +{ + lockdep_assert_held(&mm->mmap_lock); + return find_vma_non_owner(mm, addr); +} + EXPORT_SYMBOL(find_vma); /*
Current bpf-next bpf selftest "get_stack_raw_tp" triggered the warning: [ 1411.304463] WARNING: CPU: 3 PID: 140 at include/linux/mmap_lock.h:164 find_vma+0x47/0xa0 [ 1411.304469] Modules linked in: bpf_testmod(O) [last unloaded: bpf_testmod] [ 1411.304476] CPU: 3 PID: 140 Comm: systemd-journal Tainted: G W O 5.14.0+ #53 [ 1411.304479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 1411.304481] RIP: 0010:find_vma+0x47/0xa0 [ 1411.304484] Code: de 48 89 ef e8 ba f5 fe ff 48 85 c0 74 2e 48 83 c4 08 5b 5d c3 48 8d bf 28 01 00 00 be ff ff ff ff e8 2d 9f d8 00 85 c0 75 d4 <0f> 0b 48 89 de 48 8 [ 1411.304487] RSP: 0018:ffffabd440403db8 EFLAGS: 00010246 [ 1411.304490] RAX: 0000000000000000 RBX: 00007f00ad80a0e0 RCX: 0000000000000000 [ 1411.304492] RDX: 0000000000000001 RSI: ffffffff9776b144 RDI: ffffffff977e1b0e [ 1411.304494] RBP: ffff9cf5c2f50000 R08: ffff9cf5c3eb25d8 R09: 00000000fffffffe [ 1411.304496] R10: 0000000000000001 R11: 00000000ef974e19 R12: ffff9cf5c39ae0e0 [ 1411.304498] R13: 0000000000000000 R14: 0000000000000000 R15: ffff9cf5c39ae0e0 [ 1411.304501] FS: 00007f00ae754780(0000) GS:ffff9cf5fba00000(0000) knlGS:0000000000000000 [ 1411.304504] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1411.304506] CR2: 000000003e34343c CR3: 0000000103a98005 CR4: 0000000000370ee0 [ 1411.304508] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1411.304510] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 1411.304512] Call Trace: [ 1411.304517] stack_map_get_build_id_offset+0x17c/0x260 [ 1411.304528] __bpf_get_stack+0x18f/0x230 [ 1411.304541] bpf_get_stack_raw_tp+0x5a/0x70 [ 1411.305752] RAX: 0000000000000000 RBX: 5541f689495641d7 RCX: 0000000000000000 [ 1411.305756] RDX: 0000000000000001 RSI: ffffffff9776b144 RDI: ffffffff977e1b0e [ 1411.305758] RBP: ffff9cf5c02b2f40 R08: ffff9cf5ca7606c0 R09: ffffcbd43ee02c04 [ 1411.306978] bpf_prog_32007c34f7726d29_bpf_prog1+0xaf/0xd9c [ 1411.307861] R10: 0000000000000001 R11: 0000000000000044 R12: ffff9cf5c2ef60e0 [ 1411.307865] R13: 0000000000000005 R14: 0000000000000000 R15: ffff9cf5c2ef6108 [ 1411.309074] bpf_trace_run2+0x8f/0x1a0 [ 1411.309891] FS: 00007ff485141700(0000) GS:ffff9cf5fae00000(0000) knlGS:0000000000000000 [ 1411.309896] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1411.311221] syscall_trace_enter.isra.20+0x161/0x1f0 [ 1411.311600] CR2: 00007ff48514d90e CR3: 0000000107114001 CR4: 0000000000370ef0 [ 1411.312291] do_syscall_64+0x15/0x80 [ 1411.312941] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1411.313803] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 1411.314223] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 1411.315082] RIP: 0033:0x7f00ad80a0e0 [ 1411.315626] Call Trace: [ 1411.315632] stack_map_get_build_id_offset+0x17c/0x260 To reproduce, first build `test_progs` binary: make -C tools/testing/selftests/bpf -j60 and then run the binary at tools/testing/selftests/bpf directory: ./test_progs -t get_stack_raw_tp The warning is due to commit 5b78ed24e8ec("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()") which added mmap_assert_locked() in find_vma() function. The mmap_assert_locked() function asserts that mm->mmap_lock needs to be held. But this is not the case for bpf_get_stack() or bpf_get_stackid() helper (kernel/bpf/stackmap.c), which uses mmap_read_trylock_non_owner() instead. Since mm->mmap_lock is not held in bpf_get_stack[id]() use case, the above warning is emitted during test run. This patch added function find_vma_non_owner() which does not have lockdep_assert_held(&mm->mmap_lock) checking. This resolved the above warning. Cc: Luigi Rizzo <lrizzo@google.com> Suggested-by: Liam Howlett <liam.howlett@oracle.com> Fixes: 5b78ed24e8ec("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()") Signed-off-by: Yonghong Song <yhs@fb.com> --- include/linux/mm.h | 2 ++ kernel/bpf/stackmap.c | 2 +- mm/mmap.c | 10 ++++++++-- 3 files changed, 11 insertions(+), 3 deletions(-) Note: This version implemented the Liam's suggestion. If I got a better solution from Jason Gunthorpe, I will post v4.