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md/raid5: fix oops during stripe resizing
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commit b44c018cdf748b96b676ba09fdbc5b34fc443ada upstream.

KoWei reported crash during raid5 reshape:

[ 1032.252932] Oops: 0002 [OnePlusOSS#1] SMP PTI
[...]
[ 1032.252943] RIP: 0010:memcpy_erms+0x6/0x10
[...]
[ 1032.252947] RSP: 0018:ffffba1ac0c03b78 EFLAGS: 00010286
[ 1032.252949] RAX: 0000784ac0000000 RBX: ffff91bec3d09740 RCX: 0000000000001000
[ 1032.252951] RDX: 0000000000001000 RSI: ffff91be6781c000 RDI: 0000784ac0000000
[ 1032.252953] RBP: ffffba1ac0c03bd8 R08: 0000000000001000 R09: ffffba1ac0c03bf8
[ 1032.252954] R10: 0000000000000000 R11: 0000000000000000 R12: ffffba1ac0c03bf8
[ 1032.252955] R13: 0000000000001000 R14: 0000000000000000 R15: 0000000000000000
[ 1032.252958] FS:  0000000000000000(0000) GS:ffff91becf500000(0000) knlGS:0000000000000000
[ 1032.252959] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1032.252961] CR2: 0000784ac0000000 CR3: 000000031780a002 CR4: 00000000001606e0
[ 1032.252962] Call Trace:
[ 1032.252969]  ? async_memcpy+0x179/0x1000 [async_memcpy]
[ 1032.252977]  ? raid5_release_stripe+0x8e/0x110 [raid456]
[ 1032.252982]  handle_stripe_expansion+0x15a/0x1f0 [raid456]
[ 1032.252988]  handle_stripe+0x592/0x1270 [raid456]
[ 1032.252993]  handle_active_stripes.isra.0+0x3cb/0x5a0 [raid456]
[ 1032.252999]  raid5d+0x35c/0x550 [raid456]
[ 1032.253002]  ? schedule+0x42/0xb0
[ 1032.253006]  ? schedule_timeout+0x10e/0x160
[ 1032.253011]  md_thread+0x97/0x160
[ 1032.253015]  ? wait_woken+0x80/0x80
[ 1032.253019]  kthread+0x104/0x140
[ 1032.253022]  ? md_start_sync+0x60/0x60
[ 1032.253024]  ? kthread_park+0x90/0x90
[ 1032.253027]  ret_from_fork+0x35/0x40

This is because cache_size_mutex was unlocked too early in resize_stripes,
which races with grow_one_stripe() that grow_one_stripe() allocates a
stripe with wrong pool_size.

Fix this issue by unlocking cache_size_mutex after updating pool_size.

Cc: <[email protected]> # v4.4+
Reported-by: KoWei Sung <[email protected]>
Signed-off-by: Song Liu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@liu-song-6 @gregkh
liu-song-6 authored and gregkh committed Nov 10, 2020
1 parent a1632a9 commit fa4504e
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions drivers/md/raid5.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2238,8 +2238,6 @@ static int resize_stripes(struct r5conf *conf, int newsize)
} else
err = -ENOMEM;

mutex_unlock(&conf->cache_size_mutex);

conf->slab_cache = sc;
conf->active_name = 1-conf->active_name;

Expand All @@ -2262,6 +2260,8 @@ static int resize_stripes(struct r5conf *conf, int newsize)

if (!err)
conf->pool_size = newsize;
mutex_unlock(&conf->cache_size_mutex);

return err;
}

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