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Subject: Re: [PATCH v5 07/10] mmap locking API: add
 mmap_read_trylock_non_owner()
To:     Michel Lespinasse <walken@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-mm <linux-mm@kvack.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Laurent Dufour <ldufour@linux.ibm.com>,
        Matthew Wilcox <willy@infradead.org>,
        Liam Howlett <Liam.Howlett@oracle.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        David Rientjes <rientjes@google.com>,
        Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Daniel Jordan <daniel.m.jordan@oracle.com>
References: <20200422001422.232330-1-walken@google.com>
 <20200422001422.232330-8-walken@google.com>
From:   Vlastimil Babka <vbabka@suse.cz>
Message-ID: <afc8cb91-2620-99f3-9aaa-b6b2e80becba@suse.cz>
Date:   Mon, 18 May 2020 12:42:50 +0200
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On 4/22/20 2:14 AM, Michel Lespinasse wrote:
> Add a couple APIs used by kernel/bpf/stackmap.c only:
> - mmap_read_trylock_non_owner()
> - mmap_read_unlock_non_owner() (may be called from a work queue).
> 
> It's still not ideal that bpf/stackmap subverts the lock ownership
> in this way. Thanks to Peter Zijlstra for suggesting this API as the
> least-ugly way of addressing this in the short term.
> 
> Signed-off-by: Michel Lespinasse <walken@google.com>
> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>

Ugh... oh well.


Reviewed-by: Vlastimil Babka <vbabka@suse.cz>