Messages in this thread | | | Subject | Re: [PATCH] tty: use __GFP_NOWARN for user-controlled kmalloc() | From | Peter Hurley <> | Date | Thu, 4 Feb 2016 09:49:51 -0800 |
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Hi Dmitry,
Just a quick procedural note: tty patches need to be addressed to Greg.
On 02/04/2016 07:55 AM, Dmitry Vyukov wrote: > Size of kmalloc() in vc_do_resize() is controlled by user. > Too large kmalloc() size triggers WARNING message on console. > > Use __GFP_NOWARN for this kmalloc() to not scare admins. > > Signed-off-by: Dmitry Vyukov <dvyukov@google.com> > --- > Example WARNING: > > WARNING: CPU: 3 PID: 7642 at mm/page_alloc.c:2999 > __alloc_pages_nodemask+0x7d2/0x1760() > Modules linked in: > CPU: 3 PID: 7642 Comm: a.out Not tainted 4.4.0+ #276 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > 00000000ffffffff ffff88006d24f610 ffffffff82999e2d 0000000000000000 > ffff880060d9af80 ffffffff86475560 ffff88006d24f650 ffffffff81352089 > ffffffff816721e2 ffffffff86475560 0000000000000bb7 00000000024240c0 > Call Trace: > [< inline >] __dump_stack lib/dump_stack.c:15 > [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 > [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 > [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 > [< inline >] __alloc_pages_slowpath mm/page_alloc.c:2999 > [<ffffffff816721e2>] __alloc_pages_nodemask+0x7d2/0x1760 mm/page_alloc.c:3253 > [<ffffffff8174a799>] alloc_pages_current+0xe9/0x450 mm/mempolicy.c:2090 > [< inline >] alloc_pages include/linux/gfp.h:459 > [<ffffffff8166df66>] alloc_kmem_pages+0x16/0x100 mm/page_alloc.c:3433 > [<ffffffff816c698f>] kmalloc_order+0x1f/0x80 mm/slab_common.c:1008 > [<ffffffff816c6a0f>] kmalloc_order_trace+0x1f/0x140 mm/slab_common.c:1019 > [< inline >] kmalloc_large include/linux/slab.h:395 > [<ffffffff8175b624>] __kmalloc+0x2f4/0x340 mm/slub.c:3557 > [< inline >] kmalloc include/linux/slab.h:468 > [<ffffffff82d47800>] vc_do_resize+0x2c0/0x1140 drivers/tty/vt/vt.c:874 > [<ffffffff82d4878a>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:993 > [< inline >] tiocswinsz drivers/tty/tty_io.c:2357 > [<ffffffff82cf22b3>] tty_ioctl+0x1083/0x2160 drivers/tty/tty_io.c:2869 > [< inline >] vfs_ioctl fs/ioctl.c:43 > [<ffffffff817efdac>] do_vfs_ioctl+0x18c/0xfb0 fs/ioctl.c:674 > [< inline >] SYSC_ioctl fs/ioctl.c:689 > [<ffffffff817f0c5f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:680 > --- > drivers/tty/vt/vt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > index bd51bdd..2382810 100644 > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -871,7 +871,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc, > if (new_cols == vc->vc_cols && new_rows == vc->vc_rows) > return 0; > > - newscreen = kmalloc(new_screen_size, GFP_USER); > + newscreen = kmalloc(new_screen_size, GFP_USER | __GFP_NOWARN); > if (!newscreen) > return -ENOMEM; > >
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