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author | Alexey Kardashevskiy <aik@ozlabs.ru> | 2021-03-01 17:36:53 +1100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-19 10:12:58 +0200 |
commit | 6289b028b5e21974b1761206d4c49d88a766a5af (patch) | |
tree | 96819dfd69fd36b492c95a9ebe7757b43e1a5fa4 | |
parent | bece6aea3653729d517299f9c5e83bf7d23319cd (diff) | |
download | linux-stable-6289b028b5e21974b1761206d4c49d88a766a5af.tar.gz linux-stable-6289b028b5e21974b1761206d4c49d88a766a5af.tar.bz2 linux-stable-6289b028b5e21974b1761206d4c49d88a766a5af.zip |
powerpc/iommu: Annotate nested lock for lockdep
[ Upstream commit cc7130bf119add37f36238343a593b71ef6ecc1e ]
The IOMMU table is divided into pools for concurrent mappings and each
pool has a separate spinlock. When taking the ownership of an IOMMU group
to pass through a device to a VM, we lock these spinlocks which triggers
a false negative warning in lockdep (below).
This fixes it by annotating the large pool's spinlock as a nest lock
which makes lockdep not complaining when locking nested locks if
the nest lock is locked already.
===
WARNING: possible recursive locking detected
5.11.0-le_syzkaller_a+fstn1 #100 Not tainted
--------------------------------------------
qemu-system-ppc/4129 is trying to acquire lock:
c0000000119bddb0 (&(p->lock)/1){....}-{2:2}, at: iommu_take_ownership+0xac/0x1e0
but task is already holding lock:
c0000000119bdd30 (&(p->lock)/1){....}-{2:2}, at: iommu_take_ownership+0xac/0x1e0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(p->lock)/1);
lock(&(p->lock)/1);
===
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210301063653.51003-1-aik@ozlabs.ru
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | arch/powerpc/kernel/iommu.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 5b69a6a72a0e..6806eefa52ce 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -1050,7 +1050,7 @@ int iommu_take_ownership(struct iommu_table *tbl) spin_lock_irqsave(&tbl->large_pool.lock, flags); for (i = 0; i < tbl->nr_pools; i++) - spin_lock(&tbl->pools[i].lock); + spin_lock_nest_lock(&tbl->pools[i].lock, &tbl->large_pool.lock); iommu_table_release_pages(tbl); @@ -1078,7 +1078,7 @@ void iommu_release_ownership(struct iommu_table *tbl) spin_lock_irqsave(&tbl->large_pool.lock, flags); for (i = 0; i < tbl->nr_pools; i++) - spin_lock(&tbl->pools[i].lock); + spin_lock_nest_lock(&tbl->pools[i].lock, &tbl->large_pool.lock); memset(tbl->it_map, 0, sz); |