linux-kernel - Re: [PATCH] drbd: fix request leak introduced by locking/atomic, kref: Kill kref

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Message-ID: <20170511082948.wfzuh5coviinyul3@hirez.programming.kicks-ass.net>
Date:   Thu, 11 May 2017 10:29:48 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lars Ellenberg <lars.ellenberg@...bit.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Philipp Reisner <philipp.reisner@...bit.com>,
        drbd-dev@...ts.linbit.com
Subject: Re: [PATCH] drbd: fix request leak introduced by locking/atomic,
 kref: Kill kref_sub()

On Thu, May 11, 2017 at 10:21:46AM +0200, Lars Ellenberg wrote:
> Regression fix for 4.11, which totally broke DRBD
> 
> When killing kref_sub(), the unconditional additional kref_get()
> was not properly paired with the necessary kref_put(), causing
> a leak of struct drbd_requests (~ 224 Bytes) per submitted bio,
> and breaking DRBD in general, as the destructor of those "drbd_requests"
> does more than just the mempoll_free().
> 
> Fixes: bdfafc4ffdd2 ("locking/atomic, kref: Kill kref_sub()")
> Signed-off-by: Lars Ellenberg <lars.ellenberg@...bit.com>

Dang, sorry about that. Thanks for fixing it.