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Date: Fri, 10 Mar 2017 13:34:19 -0800 From: Matthew Wilcox <willy@...radead.org> To: Alexey Khoroshilov <khoroshilov@...ras.ru> Cc: Vitaly Wool <vitalywool@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Dan Streetman <ddstreet@...e.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org Subject: Re: z3fold: suspicious return with spinlock held On Sat, Mar 11, 2017 at 12:22:12AM +0300, Alexey Khoroshilov wrote: > Hello! > > z3fold_reclaim_page() contains the only return that may > leave the function with pool->lock spinlock held. > > 669 spin_lock(&pool->lock); > 670 if (kref_put(&zhdr->refcount, release_z3fold_page)) { > 671 atomic64_dec(&pool->pages_nr); > 672 return 0; > 673 } > > May be we need spin_unlock(&pool->lock); just before return? I would tend to agree. sparse warns about this, and also about two other locking problems ... which I'm not sure are really problems so much as missing annotations? mm/z3fold.c:467:35: warning: context imbalance in 'z3fold_alloc' - unexpected unlock mm/z3fold.c:519:26: warning: context imbalance in 'z3fold_free' - different lock contexts for basic block mm/z3fold.c:581:12: warning: context imbalance in 'z3fold_reclaim_page' - different lock contexts for basic block
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