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From: Davidlohr Bueso <dave@stgolabs.net>
To: Michel Lespinasse <walken@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Laurent Dufour <ldufour@linux.ibm.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	Liam Howlett <Liam.Howlett@oracle.com>,
	Jerome Glisse <jglisse@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Markus Elfring <Markus.Elfring@web.de>
Subject: Re: [PATCH v2 07/10] mmap locking API: add mmap_read_release() and mmap_read_unlock_non_owner()
Date: Thu, 26 Mar 2020 21:46:47 -0700	[thread overview]
Message-ID: <20200327044647.wgfsmjy37n72dixe@linux-p48b> (raw)
In-Reply-To: <20200327021058.221911-8-walken@google.com>

On Thu, 26 Mar 2020, Michel Lespinasse wrote:

>Add a couple APIs to allow splitting mmap_read_unlock() into two calls:
>- mmap_read_release(), called by the task that had taken the mmap lock;
>- mmap_read_unlock_non_owner(), called from a work queue.
>
>These apis are used by kernel/bpf/stackmap.c only.

I'm not crazy about the idea generalizing such calls into an mm api.
We try to stay away from non-owner semantics in locking - granted
the IS_ENABLED(CONFIG_PREEMPT_RT) warning, but still.

Could this give future users the wrong impression? What about just
using rwsem calls directly in bpf?

Thanks,
Davidlohr

  reply	other threads:[~2020-03-27  4:48 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27  2:10 [PATCH v2 00/10] Add a new mmap locking API wrapping mmap_sem calls Michel Lespinasse
2020-03-27  2:10 ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 01/10] mmap locking API: initial implementation as rwsem wrappers Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27 12:16   ` Jason Gunthorpe
2020-03-27 21:52     ` Michel Lespinasse
2020-03-27 21:52       ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 02/10] MMU notifier: use the new mmap locking API Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 03/10] DMA reservations: " Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 04/10] mmap locking API: use coccinelle to convert mmap_sem rwsem call sites Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  7:22   ` Markus Elfring
2020-03-27  7:22     ` [Cocci] " Markus Elfring
2020-03-27  7:44     ` Michel Lespinasse
2020-03-27  7:44       ` [Cocci] " Michel Lespinasse
2020-03-27  7:44       ` Michel Lespinasse
2020-03-27  8:00       ` [v2 " Markus Elfring
2020-03-27  8:00         ` [Cocci] " Markus Elfring
2020-03-27  8:08         ` Michel Lespinasse
2020-03-27  8:08           ` [Cocci] " Michel Lespinasse
2020-03-27  8:08           ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 05/10] mmap locking API: convert mmap_sem call sites missed by coccinelle Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  8:21   ` Markus Elfring
2020-03-27  8:21     ` [Cocci] " Markus Elfring
2020-03-27  2:10 ` [PATCH v2 06/10] mmap locking API: convert nested write lock sites Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 07/10] mmap locking API: add mmap_read_release() and mmap_read_unlock_non_owner() Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  4:46   ` Davidlohr Bueso [this message]
2020-03-27  5:09     ` Michel Lespinasse
2020-03-27  5:09       ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  2:10 ` [PATCH v2 09/10] mmap locking API: use lockdep_assert_held Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse
2020-03-27  4:48   ` Davidlohr Bueso
2020-03-27  2:10 ` [PATCH v2 10/10] mmap locking API: rename mmap_sem to mmap_lock Michel Lespinasse
2020-03-27  2:10   ` Michel Lespinasse

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