I've just realized that Darrick was not on the CC list. Let's add him. I believe this patch should go in in the current cycle because 5d17a73a2ebe was merged in this merge window and it can be abused... The other patch [1] is not that urgent. [1] http://lkml.kernel.org/r/20170302154541.16155-2-mhocko@xxxxxxxxxx On Thu 02-03-17 16:45:40, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxxx> > > Even though kmem_zalloc_greedy is documented it might fail the current > code doesn't really implement this properly and loops on the smallest > allowed size for ever. This is a problem because vzalloc might fail > permanently - we might run out of vmalloc space or since 5d17a73a2ebe > ("vmalloc: back off when the current task is killed") when the current > task is killed. The later one makes the failure scenario much more > probable than it used to be because it makes vmalloc() failures > permanent for tasks with fatal signals pending.. Fix this by bailing out > if the minimum size request failed. > > This has been noticed by a hung generic/269 xfstest by Xiong Zhou. > > fsstress: vmalloc: allocation failure, allocated 12288 of 20480 bytes, mode:0x14080c2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO), nodemask=(null) > fsstress cpuset=/ mems_allowed=0-1 > CPU: 1 PID: 23460 Comm: fsstress Not tainted 4.10.0-master-45554b2+ #21 > Hardware name: HP ProLiant DL380 Gen9/ProLiant DL380 Gen9, BIOS P89 10/05/2016 > Call Trace: > dump_stack+0x63/0x87 > warn_alloc+0x114/0x1c0 > ? alloc_pages_current+0x88/0x120 > __vmalloc_node_range+0x250/0x2a0 > ? kmem_zalloc_greedy+0x2b/0x40 [xfs] > ? free_hot_cold_page+0x21f/0x280 > vzalloc+0x54/0x60 > ? kmem_zalloc_greedy+0x2b/0x40 [xfs] > kmem_zalloc_greedy+0x2b/0x40 [xfs] > xfs_bulkstat+0x11b/0x730 [xfs] > ? xfs_bulkstat_one_int+0x340/0x340 [xfs] > ? selinux_capable+0x20/0x30 > ? security_capable+0x48/0x60 > xfs_ioc_bulkstat+0xe4/0x190 [xfs] > xfs_file_ioctl+0x9dd/0xad0 [xfs] > ? do_filp_open+0xa5/0x100 > do_vfs_ioctl+0xa7/0x5e0 > SyS_ioctl+0x79/0x90 > do_syscall_64+0x67/0x180 > entry_SYSCALL64_slow_path+0x25/0x25 > > fsstress keeps looping inside kmem_zalloc_greedy without any way out > because vmalloc keeps failing due to fatal_signal_pending. > > Reported-by: Xiong Zhou <xzhou@xxxxxxxxxx> > Analyzed-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> > --- > fs/xfs/kmem.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c > index 339c696bbc01..ee95f5c6db45 100644 > --- a/fs/xfs/kmem.c > +++ b/fs/xfs/kmem.c > @@ -34,6 +34,8 @@ kmem_zalloc_greedy(size_t *size, size_t minsize, size_t maxsize) > size_t kmsize = maxsize; > > while (!(ptr = vzalloc(kmsize))) { > + if (kmsize == minsize) > + break; > if ((kmsize >>= 1) <= minsize) > kmsize = minsize; > } > -- > 2.11.0 > -- Michal Hocko SUSE Labs
