mm: drop mmap_sem before calling balance_dirty_pages() in write fault

[mirror_ubuntu-jammy-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index b6a5d6a08438693e892ac63960bc044a2a62b166..9ea917e28ef4e37732bf504d09eee2b948e3a8cf 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2289,10 +2289,11 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
  *
  * The function expects the page to be locked and unlocks it.
  */
-static void fault_dirty_shared_page(struct vm_area_struct *vma,
-                                   struct page *page)
+static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
 {
+       struct vm_area_struct *vma = vmf->vma;
        struct address_space *mapping;
+       struct page *page = vmf->page;
        bool dirtied;
        bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
 
@@ -2307,16 +2308,30 @@ static void fault_dirty_shared_page(struct vm_area_struct *vma,
        mapping = page_rmapping(page);
        unlock_page(page);
 
+       if (!page_mkwrite)
+               file_update_time(vma->vm_file);
+
+       /*
+        * Throttle page dirtying rate down to writeback speed.
+        *
+        * mapping may be NULL here because some device drivers do not
+        * set page.mapping but still dirty their pages
+        *
+        * Drop the mmap_sem before waiting on IO, if we can. The file
+        * is pinning the mapping, as per above.
+        */
        if ((dirtied || page_mkwrite) && mapping) {
-               /*
-                * Some device drivers do not set page.mapping
-                * but still dirty their pages
-                */
+               struct file *fpin;
+
+               fpin = maybe_unlock_mmap_for_io(vmf, NULL);
                balance_dirty_pages_ratelimited(mapping);
+               if (fpin) {
+                       fput(fpin);
+                       return VM_FAULT_RETRY;
+               }
        }
 
-       if (!page_mkwrite)
-               file_update_time(vma->vm_file);
+       return 0;
 }
 
 /*
@@ -2571,6 +2586,7 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
        __releases(vmf->ptl)
 {
        struct vm_area_struct *vma = vmf->vma;
+       vm_fault_t ret = VM_FAULT_WRITE;
 
        get_page(vmf->page);
 
@@ -2594,10 +2610,10 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf)
                wp_page_reuse(vmf);
                lock_page(vmf->page);
        }
-       fault_dirty_shared_page(vma, vmf->page);
+       ret |= fault_dirty_shared_page(vmf);
        put_page(vmf->page);
 
-       return VM_FAULT_WRITE;
+       return ret;
 }
 
 /*
@@ -3641,7 +3657,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
                return ret;
        }
 
-       fault_dirty_shared_page(vma, vmf->page);
+       ret |= fault_dirty_shared_page(vmf);
        return ret;
 }