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[34.16.174.112]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-37c5228eb5bsm483197a91.12.2026.06.15.13.43.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jun 2026 13:43:09 -0700 (PDT) Date: Mon, 15 Jun 2026 20:43:04 +0000 From: Carlos Llamas To: Dave Hansen Cc: linux-kernel@vger.kernel.org, Alice Ryhl , Andrew Morton , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Christian Brauner , David Ahern , "David S. Miller" , Greg Kroah-Hartman , "Liam R. Howlett" , linux-mm@kvack.org, Lorenzo Stoakes , netdev@vger.kernel.org, Shakeel Butt , Suren Baghdasaryan , Todd Kjos , Vlastimil Babka Subject: Re: [PATCH v2 4/5] binder: Remove mmap_lock fallback Message-ID: References: <20260610230409.A44D29FA@davehans-spike.ostc.intel.com> <20260610230417.77D64DBB@davehans-spike.ostc.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260610230417.77D64DBB@davehans-spike.ostc.intel.com> On Wed, Jun 10, 2026 at 04:04:17PM -0700, Dave Hansen wrote: > > From: Dave Hansen > > Previously, the per-VMA locking could fail in the face of writers > which necessitate a fallback to mmap_lock. The new > vma_start_read_unlocked() will wait for writers instead of failing. > > Use the new helper. Wait for writers. Remove the fallback to mmap_lock. > > Signed-off-by: Dave Hansen > Acked-by: Lorenzo Stoakes > Reviewed-by: Suren Baghdasaryan > Cc: Andrew Morton > Cc: "Liam R. Howlett" > Cc: Vlastimil Babka > Cc: Shakeel Butt > Cc: linux-mm@kvack.org > Cc: Greg Kroah-Hartman > Cc: Arve Hjønnevåg > Cc: Todd Kjos > Cc: Christian Brauner > Cc: Carlos Llamas > Cc: Alice Ryhl > Cc: "David S. Miller" > Cc: David Ahern > Cc: netdev@vger.kernel.org > > --- > > b/drivers/android/binder_alloc.c | 17 +++++------------ > 1 file changed, 5 insertions(+), 12 deletions(-) > > diff -puN drivers/android/binder_alloc.c~binder-vma-waiter drivers/android/binder_alloc.c > --- a/drivers/android/binder_alloc.c~binder-vma-waiter 2026-06-10 15:57:56.419452721 -0700 > +++ b/drivers/android/binder_alloc.c 2026-06-10 15:57:56.423452863 -0700 > @@ -259,21 +259,14 @@ static int binder_page_insert(struct bin > struct vm_area_struct *vma; > int ret = -ESRCH; > > - /* attempt per-vma lock first */ > - vma = lock_vma_under_rcu(mm, addr); > - if (vma) { > - if (binder_alloc_is_mapped(alloc)) > - ret = vm_insert_page(vma, addr, page); > - vma_end_read(vma); > + vma = vma_start_read_unlocked(mm, addr); > + if (!vma) > return ret; > - } > > - /* fall back to mmap_lock */ > - mmap_read_lock(mm); > - vma = vma_lookup(mm, addr); > - if (vma && binder_alloc_is_mapped(alloc)) > + if (binder_alloc_is_mapped(alloc)) > ret = vm_insert_page(vma, addr, page); > - mmap_read_unlock(mm); > + > + vma_end_read(vma); > > return ret; > } > _ Thanks, Acked-by: Carlos Llamas