On Mon, 2014-03-03 at 19:26 -0800, Linus Torvalds wrote: > On Mon, Mar 3, 2014 at 7:13 PM, Davidlohr Bueso <davidlohr@xxxxxx> wrote: > > > > Yes, I shortly realized that was silly... but I can say for sure it can > > happen and a quick qemu run confirms it. So I see your point as to > > asking why we need it, so now I'm looking for an explanation in the > > code. > > We definitely *do* have users. > > One example would be ptrace -> access_process_vm -> __access_remote_vm > -> get_user_pages() -> find_extend_vma() -> find_vma_prev -> find_vma. And: [ 4.274542] Call Trace: [ 4.274747] [<ffffffff81809525>] dump_stack+0x46/0x58 [ 4.275069] [<ffffffff811331ee>] vmacache_find+0xae/0xc0 [ 4.275425] [<ffffffff8113c840>] find_vma+0x20/0x80 [ 4.275625] [<ffffffff8113e5cb>] find_extend_vma+0x2b/0x90 [ 4.275982] [<ffffffff81138a09>] __get_user_pages+0x99/0x5a0 [ 4.276427] [<ffffffff81137b0b>] ? follow_page_mask+0x32b/0x400 [ 4.276671] [<ffffffff81138fc2>] get_user_pages+0x52/0x60 [ 4.276886] [<ffffffff81167dc3>] copy_strings.isra.20+0x1a3/0x2f0 [ 4.277239] [<ffffffff81167f4d>] copy_strings_kernel+0x3d/0x50 [ 4.277472] [<ffffffff811b3688>] load_script+0x1e8/0x280 [ 4.277692] [<ffffffff81167d0a>] ? copy_strings.isra.20+0xea/0x2f0 [ 4.277931] [<ffffffff81167ff7>] search_binary_handler+0x97/0x1d0 [ 4.278288] [<ffffffff811694bf>] do_execve_common.isra.28+0x4ef/0x650 [ 4.278544] [<ffffffff81169638>] do_execve+0x18/0x20 [ 4.278754] [<ffffffff8116984e>] SyS_execve+0x2e/0x40 [ 4.278960] [<ffffffff8181b549>] stub_execve+0x69/0xa0 -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>