[PATCH AUTOSEL 4.18 013/126] lightnvm: pblk: fix two sleep-in-atomic-context bugs

Sasha Levin
2018-10-31T23:40:31Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 7325b4bbe5952e3e939f15de812f2ee0c0d33ca9 ]

The driver may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] nvm_dev_dma_alloc(GFP_KERNEL)
drivers/lightnvm/pblk-core.c, 754:
nvm_dev_dma_alloc in pblk_line_submit_smeta_io
drivers/lightnvm/pblk-core.c, 1048:
pblk_line_submit_smeta_io in pblk_line_init_bb
drivers/lightnvm/pblk-core.c, 1434:
pblk_line_init_bb in pblk_line_replace_data
drivers/lightnvm/pblk-recovery.c, 980:
pblk_line_replace_data in pblk_recov_l2p
drivers/lightnvm/pblk-recovery.c, 976:
spin_lock in pblk_recov_l2p

[FUNC] bio_map_kern(GFP_KERNEL)
drivers/lightnvm/pblk-core.c, 762:
bio_map_kern in pblk_line_submit_smeta_io
drivers/lightnvm/pblk-core.c, 1048:
pblk_line_submit_smeta_io in pblk_line_init_bb
drivers/lightnvm/pblk-core.c, 1434:
pblk_line_init_bb in pblk_line_replace_data
drivers/lightnvm/pblk-recovery.c, 980:
pblk_line_replace_data in pblk_recov_l2p
drivers/lightnvm/pblk-recovery.c, 976:
spin_lock in pblk_recov_l2p

To fix these bugs, the call to pblk_line_replace_data()
is moved out of the spinlock protection.

These bugs are found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/lightnvm/pblk-recovery.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
index d83466b3821b..958bda8a69b7 100644
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -956,12 +956,14 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
}
}

- spin_lock(&l_mg->free_lock);
if (!open_lines) {
+ spin_lock(&l_mg->free_lock);
WARN_ON_ONCE(!test_and_clear_bit(meta_line,
&l_mg->meta_bitmap));
+ spin_unlock(&l_mg->free_lock);
pblk_line_replace_data(pblk);
} else {
+ spin_lock(&l_mg->free_lock);
/* Allocate next line for preparation */
l_mg->data_next = pblk_line_get(pblk);
if (l_mg->data_next) {
@@ -969,8 +971,8 @@ struct pblk_line *pblk_recov_l2p(struct pblk *pblk)
l_mg->data_next->type = PBLK_LINETYPE_DATA;
is_next = 1;
}
+ spin_unlock(&l_mg->free_lock);
}
- spin_unlock(&l_mg->free_lock);

if (is_next)
pblk_line_erase(pblk, l_mg->data_next);
--
2.17.1