forked from luck/tmp_suning_uos_patched
md/raid5: fix locking in handle_stripe_clean_event()
After commit566c09c534
("raid5: relieve lock contention in get_active_stripe()") __find_stripe() is called under conf->hash_locks + hash. But handle_stripe_clean_event() calls remove_hash() under conf->device_lock. Under some cirscumstances the hash chain can be circuited, and we get an infinite loop with disabled interrupts and locked hash lock in __find_stripe(). This leads to hard lockup on multiple CPUs and following system crash. I was able to reproduce this behavior on raid6 over 6 ssd disks. The devices_handle_discard_safely option should be set to enable trim support. The following script was used: for i in `seq 1 32`; do dd if=/dev/zero of=large$i bs=10M count=100 & done neilb: original was against a 3.x kernel. I forward-ported to 4.3-rc. This verison is suitable for any kernel since Commit:59fc630b8b
("RAID5: batch adjacent full stripe write") (v4.1+). I'll post a version for earlier kernels to stable. Signed-off-by: Roman Gushchin <klamm@yandex-team.ru> Fixes:566c09c534
("raid5: relieve lock contention in get_active_stripe()") Signed-off-by: NeilBrown <neilb@suse.com> Cc: Shaohua Li <shli@kernel.org> Cc: <stable@vger.kernel.org> # 3.13 - 4.2
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parent
8bce6d35b3
commit
b8a9d66d04
@ -3499,6 +3499,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
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}
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if (!discard_pending &&
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test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
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int hash;
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clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
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clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
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if (sh->qd_idx >= 0) {
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@ -3512,16 +3513,17 @@ static void handle_stripe_clean_event(struct r5conf *conf,
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* no updated data, so remove it from hash list and the stripe
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* will be reinitialized
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*/
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spin_lock_irq(&conf->device_lock);
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unhash:
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hash = sh->hash_lock_index;
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spin_lock_irq(conf->hash_locks + hash);
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remove_hash(sh);
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spin_unlock_irq(conf->hash_locks + hash);
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if (head_sh->batch_head) {
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sh = list_first_entry(&sh->batch_list,
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struct stripe_head, batch_list);
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if (sh != head_sh)
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goto unhash;
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}
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spin_unlock_irq(&conf->device_lock);
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sh = head_sh;
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if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
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