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Howlett" , linux-mm@kvack.org, Lorenzo Stoakes , Shakeel Butt , Suren Baghdasaryan , Vlastimil Babka From: Dave Hansen Date: Wed, 29 Apr 2026 11:20:00 -0700 References: <20260429181954.F50224AE@davehans-spike.ostc.intel.com> In-Reply-To: <20260429181954.F50224AE@davehans-spike.ostc.intel.com> Message-Id: <20260429182000.93887DFB@davehans-spike.ostc.intel.com> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9803340008 X-Rspam-User: X-Stat-Signature: pupbazyq5impscdsbjbyhiqnsbqg6rqi X-HE-Tag: 1777486803-992777 X-HE-Meta: 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 YO1JBPPv 7HyUhn1B9wSyDizP9z1dqAL0CdppD7XQNOLyapDo+8pngMsNS3Z7QcNASjc+3ydKB9oH3SbzfrAPUDfxT9StRLk90Ycmd4C1td7z/0TTiSIvo4Vc4AVX8JTsANC7NTIAAn9CyTkr6EuBNpOxFaCluo7iwfVt9lba2/xF/T6BSKGcfoNKvi8jdFnpcUcncVw/cd6Ic7PUjaSK85eU+gAD98tMiciNiawW3bGMKwLNQgj04T9d7rLFwB7pVlVMaZYo2N3+VUUZG/IWJCA0oCvWYgq8obZ4QHpGUl59KuiDb+qkAkf7/5HeUVuoyw0Jz2XbkaNdVlXPCPfJYqJmOyEa6gpTMVbwRGDl0ieC/0MOMzC1nJ9BxXiXSuZCDxuMLmpnp0tAsQ/joyRAqQVfpxCAVMS7jmRHB1Cvbsy2L Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Dave Hansen Previously, the per-VMA locking could fail in the face of writers which necessitate a fallback to mmap_lock. The new lock_vma_under_rcu_wait() 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 Cc: Suren Baghdasaryan Cc: Andrew Morton Cc: "Liam R. Howlett" Cc: Lorenzo Stoakes Cc: Vlastimil Babka Cc: Shakeel Butt Cc: linux-mm@kvack.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 2026-04-29 11:18:51.307654829 -0700 +++ b/drivers/android/binder_alloc.c 2026-04-29 11:18:51.310654944 -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 = lock_vma_under_rcu_wait(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; } _