On Sun, Jan 18, 2015 at 2:34 PM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote: > On 06/24/2014 04:16 PM, Konstantin Khlebnikov wrote: >> This patch prints warning (if CONFIG_DEBUG_VM=y) when >> memory commitment becomes too negative. >> >> Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx> > > Hi Konstantin, > > I seem to be hitting this warning when fuzzing on the latest -next kernel: That might be unexpected change of shmem file which holds anon-vma data, thanks to checkpoint-restore they are expoted via /proc/.../map_files I've fixed truncate (https://lkml.org/lkml/2014/6/24/729) but there are some other ways to change i_size: write, fallocate and maybe something else. We could seal this promblem (literally). --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3355,6 +3355,9 @@ static struct file *__shmem_file_setup(const char *name, loff_t size, if (!inode) goto put_memory; + if (!(flags & VM_NORESERVE)) + SHMEM_I(inode)->seals |= F_SEAL_SHRINK | F_SEAL_GROW; + inode->i_flags |= i_flags; d_instantiate(path.dentry, inode); inode->i_size = size; > > [ 683.674323] ------------[ cut here ]------------ > [ 683.675552] WARNING: CPU: 12 PID: 25654 at mm/mmap.c:157 __vm_enough_memory+0x1b7/0x1d0() > [ 683.676972] memory commitment underflow > [ 683.678212] Modules linked in: > [ 683.678219] CPU: 12 PID: 25654 Comm: trinity-c373 Not tainted 3.19.0-rc4-next-20150116-sasha-00054-g4ad498c-dirty #1744 > [ 683.678227] ffffffff9c6f7e73 ffff8802c0883a58 ffffffff9b439fb2 0000000000000000 > [ 683.678231] ffff8802c0883aa8 ffff8802c0883a98 ffffffff98159e1a ffff8802c0883ae8 > [ 683.678236] 0000000000000001 0000000000000000 ffffffffffff76f1 ffff8802a9749000 > [ 683.678243] Call Trace: > [ 683.678288] dump_stack (lib/dump_stack.c:52) > [ 683.678297] warn_slowpath_common (kernel/panic.c:447) > [ 683.678302] warn_slowpath_fmt (kernel/panic.c:461) > [ 683.678307] __vm_enough_memory (mm/mmap.c:157 (discriminator 3)) > [ 683.678317] cap_vm_enough_memory (security/commoncap.c:958) > [ 683.678323] security_vm_enough_memory_mm (security/security.c:212) > [ 683.678331] shmem_getpage_gfp (mm/shmem.c:1161) > [ 683.678337] shmem_write_begin (mm/shmem.c:1495) > [ 683.678343] generic_perform_write (mm/filemap.c:2491) > [ 683.678447] __generic_file_write_iter (mm/filemap.c:2632) > [ 683.678452] generic_file_write_iter (mm/filemap.c:2659) > [ 683.678458] do_iter_readv_writev (fs/read_write.c:680) > [ 683.678461] do_readv_writev (fs/read_write.c:848) > [ 683.678512] vfs_writev (fs/read_write.c:893) > [ 683.678515] SyS_writev (fs/read_write.c:926 fs/read_write.c:917) > [ 683.678520] tracesys_phase2 (arch/x86/kernel/entry_64.S:529) > > > Thanks, > Sasha -- 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>