On Thu, Mar 29, 2018 at 11:42:04AM +0900, Minchan Kim wrote: > > On Thu, Mar 29, 2018 at 11:37:12AM +0900, Minchan Kim wrote: > > binder_update_page_range needs down_write of mmap_sem because > > vm_insert_page need to change vma->vm_flags to VM_MIXEDMAP unless > > it is set. However, when I profile binder working, it seems > > every binder buffers should be mapped in advance by binder_mmap. > > It means we could set VM_MIXEDMAP in bider_mmap time which is > > already hold a mmap_sem as down_write so binder_update_page_range > > doesn't need to hold a mmap_sem as down_write. > > > > Android suffers from mmap_sem contention so let's reduce mmap_sem > > down_write. > > > > Cc: Todd Kjos <tk...@google.com> > > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > > Cc: Arve Hjønnevåg <a...@android.com> > > Reviewed-by: Martijn Coenen <m...@android.com> > > Signed-off-by: Minchan Kim <minc...@kernel.org> > > Sent wrong version. Sorry for that. Please ignore this and take it. > > >From 480e992d4a650fb98e1397114d75dea7af8e6d0c Mon Sep 17 00:00:00 2001 > From: Minchan Kim <minc...@kernel.org> > Date: Wed, 28 Mar 2018 11:32:42 +0900 > Subject: [PATCH v3] ANDROID: binder: change down_write to down_read > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit
<snip> I really don't want to hand-edit patches, please just send v4. thanks, greg k-h
