[PATCH] android: binder: Drop lru lock in isolate callback

[Sherry Yang]

Drop the global lru lock in isolate callback
before calling zap_page_range which calls
cond_resched, and re-acquire the global lru
lock before returning. Also change return
code to LRU_REMOVED_RETRY.

Use mmput_async when fail to acquire mmap sem
in an atomic context.

Fix "BUG: sleeping function called from invalid context"
errors when CONFIG_DEBUG_ATOMIC_SLEEP is enabled.

Fixes: f2517eb76f1f2 ("android: binder: Add global lru shrinker to binder")
Reported-by: Kyle Yan <k...@codeaurora.org>
Acked-by: Arve Hjønnevåg <a...@android.com>
Signed-off-by: Sherry Yang <sher...@android.com>
---
 drivers/android/binder_alloc.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 8fe165844e47..064f5e31ec55 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -913,6 +913,7 @@ enum lru_status binder_alloc_free_page(struct list_head 
*item,
        struct binder_alloc *alloc;
        uintptr_t page_addr;
        size_t index;
+       struct vm_area_struct *vma;
 
        alloc = page->alloc;
        if (!mutex_trylock(&alloc->mutex))
@@ -923,16 +924,22 @@ enum lru_status binder_alloc_free_page(struct list_head 
*item,
 
        index = page - alloc->pages;
        page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
-       if (alloc->vma) {
+       vma = alloc->vma;
+       if (vma) {
                mm = get_task_mm(alloc->tsk);
                if (!mm)
                        goto err_get_task_mm_failed;
                if (!down_write_trylock(&mm->mmap_sem))
                        goto err_down_write_mmap_sem_failed;
+       }
+
+       list_lru_isolate(lru, item);
+       spin_unlock(lock);
 
+       if (vma) {
                trace_binder_unmap_user_start(alloc, index);
 
-               zap_page_range(alloc->vma,
+               zap_page_range(vma,
                               page_addr + alloc->user_buffer_offset,
                               PAGE_SIZE);
 
@@ -950,13 +957,12 @@ enum lru_status binder_alloc_free_page(struct list_head 
*item,
 
        trace_binder_unmap_kernel_end(alloc, index);
 
-       list_lru_isolate(lru, item);
-
+       spin_lock(lock);
        mutex_unlock(&alloc->mutex);
-       return LRU_REMOVED;
+       return LRU_REMOVED_RETRY;
 
 err_down_write_mmap_sem_failed:
-       mmput(mm);
+       mmput_async(mm);
 err_get_task_mm_failed:
 err_page_already_freed:
        mutex_unlock(&alloc->mutex);
-- 
2.11.0 (Apple Git-81)

_______________________________________________
devel mailing list
de...@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel