| Message ID | 20210909155000.1610299-1-yhs@fb.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [bpf-next/mm,v5] bpf/mm: fix lockdep warning triggered by stack_map_get_build_id_offset() | expand |
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com> * Yonghong Song <yhs@fb.com> [210909 11:50]: > 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 fixed the issue by (1). using mmap_read_trylock() instead of > mmap_read_trylock_non_owner() to satisfy lockdep checking in find_vma(), > and (2). droping lockdep for mmap_lock right before the irq_work_queue(). > The function mmap_read_trylock_non_owner() is also removed since after > this patch nobody calls it any more. > > Cc: Luigi Rizzo <lrizzo@google.com> > Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> > Fixes: 5b78ed24e8ec("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()") > Signed-off-by: Yonghong Song <yhs@fb.com> > --- > include/linux/mmap_lock.h | 9 --------- > kernel/bpf/stackmap.c | 10 ++++++++-- > 2 files changed, 8 insertions(+), 11 deletions(-) > > diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h > index 0540f0156f58..3af8f7fb067d 100644 > --- a/include/linux/mmap_lock.h > +++ b/include/linux/mmap_lock.h > @@ -144,15 +144,6 @@ static inline void mmap_read_unlock(struct mm_struct *mm) > __mmap_lock_trace_released(mm, false); > } > > -static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm) > -{ > - if (mmap_read_trylock(mm)) { > - rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_); > - return true; > - } > - return false; > -} > - > static inline void mmap_read_unlock_non_owner(struct mm_struct *mm) > { > up_read_non_owner(&mm->mmap_lock); > diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c > index e8eefdf8cf3e..09a3fd97d329 100644 > --- a/kernel/bpf/stackmap.c > +++ b/kernel/bpf/stackmap.c > @@ -179,7 +179,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, > * with build_id. > */ > if (!user || !current || !current->mm || irq_work_busy || > - !mmap_read_trylock_non_owner(current->mm)) { > + !mmap_read_trylock(current->mm)) { > /* cannot access current->mm, fall back to ips */ > for (i = 0; i < trace_nr; i++) { > id_offs[i].status = BPF_STACK_BUILD_ID_IP; > @@ -204,9 +204,15 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, > } > > if (!work) { > - mmap_read_unlock_non_owner(current->mm); > + mmap_read_unlock(current->mm); > } else { > work->mm = current->mm; > + > + /* The lock will be released once we're out of interrupt > + * context. Tell lockdep that we've released it now so > + * it doesn't complain that we forgot to release it. > + */ > + rwsem_release(¤t->mm->mmap_lock.dep_map, _RET_IP_); > irq_work_queue(&work->irq_work); > } > } > -- > 2.30.2 > >
Hello: This patch was applied to bpf/bpf.git (refs/heads/master): On Thu, 9 Sep 2021 08:49:59 -0700 you wrote: > 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 > > [...] Here is the summary with links: - [bpf-next/mm,v5] bpf/mm: fix lockdep warning triggered by stack_map_get_build_id_offset() https://git.kernel.org/bpf/bpf/c/2f1aaf3ea666 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 0540f0156f58..3af8f7fb067d 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -144,15 +144,6 @@ static inline void mmap_read_unlock(struct mm_struct *mm) __mmap_lock_trace_released(mm, false); } -static inline bool mmap_read_trylock_non_owner(struct mm_struct *mm) -{ - if (mmap_read_trylock(mm)) { - rwsem_release(&mm->mmap_lock.dep_map, _RET_IP_); - return true; - } - return false; -} - static inline void mmap_read_unlock_non_owner(struct mm_struct *mm) { up_read_non_owner(&mm->mmap_lock); diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index e8eefdf8cf3e..09a3fd97d329 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -179,7 +179,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, * with build_id. */ if (!user || !current || !current->mm || irq_work_busy || - !mmap_read_trylock_non_owner(current->mm)) { + !mmap_read_trylock(current->mm)) { /* cannot access current->mm, fall back to ips */ for (i = 0; i < trace_nr; i++) { id_offs[i].status = BPF_STACK_BUILD_ID_IP; @@ -204,9 +204,15 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, } if (!work) { - mmap_read_unlock_non_owner(current->mm); + mmap_read_unlock(current->mm); } else { work->mm = current->mm; + + /* The lock will be released once we're out of interrupt + * context. Tell lockdep that we've released it now so + * it doesn't complain that we forgot to release it. + */ + rwsem_release(¤t->mm->mmap_lock.dep_map, _RET_IP_); irq_work_queue(&work->irq_work); } }
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 fixed the issue by (1). using mmap_read_trylock() instead of mmap_read_trylock_non_owner() to satisfy lockdep checking in find_vma(), and (2). droping lockdep for mmap_lock right before the irq_work_queue(). The function mmap_read_trylock_non_owner() is also removed since after this patch nobody calls it any more. Cc: Luigi Rizzo <lrizzo@google.com> Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> Fixes: 5b78ed24e8ec("mm/pagemap: add mmap_assert_locked() annotations to find_vma*()") Signed-off-by: Yonghong Song <yhs@fb.com> --- include/linux/mmap_lock.h | 9 --------- kernel/bpf/stackmap.c | 10 ++++++++-- 2 files changed, 8 insertions(+), 11 deletions(-)