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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>,
        =?UTF-8?q?Javier=20Gonz=C3=A1lez?= <javier@cnexlabs.com>,
        =?UTF-8?q?Matias=20Bj=C3=B8rling?= <mb@lightnvm.io>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 061/361] lightnvm: pblk: fix two sleep-in-atomic-context bugs
Date:   Sun, 11 Nov 2018 14:16:48 -0800
Message-Id: <20181111221628.496312533@linuxfoundation.org>
In-Reply-To: <20181111221619.915519183@linuxfoundation.org>
References: <20181111221619.915519183@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/lightnvm/pblk-recovery.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -956,12 +956,14 @@ next:
 		}
 	}
 
-	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 @@ next:
 			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);