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Subject[PATCH v2] lightnvm: pblk-recovery: lightnvm: pblk: Fix two sleep-in-atomic-context bugs
Date
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>
---
v2:
* Move the call to pblk_line_replace_data() out of the spinlock
protection, instead of v1 that changes GFP_KERNEL to GFP_ATOMIC in
the calls to bio_map_kern() and nvm_dev_dma_alloc().
Thanks Javier for good advice.
---
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 3a5069183859..5fde414d78bb 100644
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -955,12 +955,14 @@ 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) {
@@ -968,8 +970,8 @@ 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);
--
2.17.0
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