On Sat, Nov 19, 2011 at 3:50 AM, Hillf Danton <dhillf@xxxxxxxxx> wrote: > The flag, FAULT_FLAG_ALLOW_RETRY, was introduced by the patch, > > mm: retry page fault when blocking on disk transfer > commit: d065bd810b6deb67d4897a14bfe21f8eb526ba99 > > for reducing mmap_sem hold times that are caused by waiting for disk > transfers when accessing file mapped VMAs. > > To break COW, handle_mm_fault() is repeated with mmap_sem held, where > the introduced flag could be used again. > > The straight way is to add changes in break_ksm(), but the function could be > under write-mode mmap_sem, so it has to be dupilcated. > > Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx> I have to concur with Hugh here - FAULT_FLAG_ALLOW_RETRY was introduced to avoid holding mmap_sem while we block on a disk read, but you shouldn't hit this case in the break COW case, so there seems to be little point in adding the flag there. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href