From: Daniel Jordan <daniel.m.jordan@oracle.com>
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>,
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>
Subject: Re: [PATCH v4 07/10] mmap locking API: add mmap_read_trylock_non_owner()
Date: Mon, 20 Apr 2020 14:22:11 -0400 [thread overview]
Message-ID: <20200420182211.exrzkszefraeylv2@ca-dmjordan1.us.oracle.com> (raw)
In-Reply-To: <20200415004353.130248-8-walken@google.com>
On Tue, Apr 14, 2020 at 05:43:50PM -0700, Michel Lespinasse wrote:
> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
> index 11d41f0c7005..998968659892 100644
> --- a/kernel/bpf/stackmap.c
> +++ b/kernel/bpf/stackmap.c
> @@ -317,7 +316,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
> * with build_id.
> */
> if (!user || !current || !current->mm || irq_work_busy ||
> - mmap_read_trylock(current->mm) == 0) {
> + !mmap_read_trylock_non_owner(current->mm)) {
> /* cannot access current->mm, fall back to ips */
> for (i = 0; i < trace_nr; i++) {
> id_offs[i].status = BPF_STACK_BUILD_ID_IP;
> @@ -342,16 +341,10 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
> }
>
> if (!work) {
> - mmap_read_unlock(current->mm);
> + mmap_read_unlock_non_owner(current->mm);
These 'non_owner' calls are not intuitive because current _is the owner, so the
v3 version seems better, even if it adds a special wrapper for rwsem_release.
Though it makes some sense if you think, "we're consistently using the
non_owner APIs because there's a legitimate use somewhere else," so I'm fine
either way.
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
next prev parent reply other threads:[~2020-04-20 18:21 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 0:43 [PATCH v4 00/10] Add a new mmap locking API wrapping mmap_sem calls Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 01/10] mmap locking API: initial implementation as rwsem wrappers Michel Lespinasse
2020-04-20 19:48 ` Davidlohr Bueso
2020-04-21 0:48 ` Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 02/10] MMU notifier: use the new mmap locking API Michel Lespinasse
2020-04-20 19:51 ` Davidlohr Bueso
2020-04-15 0:43 ` [PATCH v4 03/10] DMA reservations: " Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 04/10] mmap locking API: use coccinelle to convert mmap_sem rwsem call sites Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 05/10] mmap locking API: convert mmap_sem call sites missed by coccinelle Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 06/10] mmap locking API: convert nested write lock sites Michel Lespinasse
2020-04-20 18:19 ` Daniel Jordan
2020-04-20 19:33 ` Matthew Wilcox
2020-04-21 0:51 ` Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 07/10] mmap locking API: add mmap_read_trylock_non_owner() Michel Lespinasse
2020-04-20 18:22 ` Daniel Jordan [this message]
2020-04-20 19:23 ` Matthew Wilcox
2020-04-21 0:55 ` Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER Michel Lespinasse
2020-04-20 18:23 ` Daniel Jordan
2020-04-20 19:28 ` Matthew Wilcox
2020-04-21 0:57 ` Michel Lespinasse
2020-04-15 0:43 ` [PATCH v4 09/10] mmap locking API: use lockdep_assert_held Michel Lespinasse
2020-04-21 2:35 ` Matthew Wilcox
2020-04-15 0:43 ` [PATCH v4 10/10] mmap locking API: rename mmap_sem to mmap_lock Michel Lespinasse
2020-04-20 18:28 ` Daniel Jordan
2020-04-21 5:33 ` kbuild test robot
2020-04-21 22:19 ` Michel Lespinasse
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