Commit 7370f8e1 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

mm: use vma_start_write_killable() in dup_mmap() 

Allow waiting for the VMA write lock to be interrupted by fatal signals. 
The explicit check for fatal_signal_pending() can be removed as it is
checked during vma_start_write_killable().  Improves the latency of
killing the task as we do not wait for the reader to finish before
checking for signals.

Link: https://lkml.kernel.org/r/20251110203204.1454057-3-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarSuren Baghdasaryan <surenb@google.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Chris Li <chriscli@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2197bb60

mm/mmap.c

+3 −9
Original line number Diff line number Diff line
@@ -1747,7 +1747,9 @@ __latent_entropy int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 
	for_each_vma(vmi, mpnt) {

		struct file *file;



		vma_start_write(mpnt);

		retval = vma_start_write_killable(mpnt);

		if (retval < 0)

			goto loop_out;

		if (mpnt->vm_flags & VM_DONTCOPY) {

			retval = vma_iter_clear_gfp(&vmi, mpnt->vm_start,

						    mpnt->vm_end, GFP_KERNEL);
@@ -1758,14 +1760,6 @@ __latent_entropy int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 
			continue;

		}

		charge = 0;

		/*

		 * Don't duplicate many vmas if we've been oom-killed (for

		 * example)

		 */

		if (fatal_signal_pending(current)) {

			retval = -EINTR;

			goto loop_out;

		}

		if (mpnt->vm_flags & VM_ACCOUNT) {

			unsigned long len = vma_pages(mpnt);