On Fri, Dec 05, 2014 at 09:07:07PM +0530, Anand Moon wrote: > Use GFP_ATOMIC instead of GFP_KERNEL and update for kzalloc > while we're here to fix this bug. > > [ 32.979662] ------------[ cut here ]------------ > [ 32.982865] WARNING: CPU: 3 PID: 1933 at kernel/locking/lockdep.c:2744 > lockdep_trace_alloc+0xc0/0xfc() > [ 32.983409] _cpu_up: attempt to bring up CPU 6 failed > [ 32.997141] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) > [ 33.002511] Modules linked in: > [ 33.005697] CPU: 3 PID: 1933 Comm: systemd-udevd Not tainted 3.17.4-arm7 > #11 > [ 33.012783] [<c0013dc8>] (unwind_backtrace) from [<c0011210>] > (show_stack+0x10/0x14) > [ 33.020492] [<c0011210>] (show_stack) from [<c05df5f0>] > (dump_stack+0x80/0xac) > [ 33.027679] [<c05df5f0>] (dump_stack) from [<c0024594>] > (warn_slowpath_common+0x60/0x84) > [ 33.035715] [<c0024594>] (warn_slowpath_common) from [<c00245e4>] > (warn_slowpath_fmt+0x2c/0x3c) > [ 33.044408] [<c00245e4>] (warn_slowpath_fmt) from [<c006ca54>] > (lockdep_trace_alloc+0xc0/0xfc) > [ 33.052983] [<c006ca54>] (lockdep_trace_alloc) from [<c01018d0>] > (__kmalloc+0x50/0x1c0) > [ 33.060982] [<c01018d0>] (__kmalloc) from [<c016ca28>] > (kernfs_fop_write+0x44/0x154) > [ 33.068674] [<c016ca28>] (kernfs_fop_write) from [<c01114fc>] > (vfs_write+0xb8/0x170) > [ 33.076396] [<c01114fc>] (vfs_write) from [<c0111a38>] > (SyS_write+0x40/0x80) > [ 33.083392] [<c0111a38>] (SyS_write) from [<c000dce0>] > (ret_fast_syscall+0x0/0x48) > [ 33.090904] ---[ end trace 48da1fd0929e78f5 ]--- > [ 33.095503] BUG: sleeping function called from invalid context at > mm/slub.c:1250 > [ 33.102878] in_atomic(): 0, irqs_disabled(): 128, pid: 1933, name: > systemd-udevd > [ 33.110235] INFO: lockdep is turned off. > [ 33.114122] irq event stamp: 76128 > [ 33.117484] hardirqs last enabled at (76127): [<c05e5808>] > _raw_spin_unlock_irq+0x24/0x44 > [ 33.125723] hardirqs last disabled at (76128): [<c0010b20>] > do_work_pending+0x6c/0xc4 > [ 33.133532] softirqs last enabled at (75542): [<c00283b0>] > __do_softirq+0x1e8/0x270 > [ 33.141244] softirqs last disabled at (75529): [<c00286f4>] > irq_exit+0x84/0xf4 > [ 33.148431] CPU: 3 PID: 1933 Comm: systemd-udevd Tainted: G W > 3.17.4-arm7 #11 > [ 33.156626] [<c0013dc8>] (unwind_backtrace) from [<c0011210>] > (show_stack+0x10/0x14) > [ 33.164334] [<c0011210>] (show_stack) from [<c05df5f0>] > (dump_stack+0x80/0xac) > [ 33.171523] [<c05df5f0>] (dump_stack) from [<c01018e8>] > (__kmalloc+0x68/0x1c0) > [ 33.178719] [<c01018e8>] (__kmalloc) from [<c016ca28>] > (kernfs_fop_write+0x44/0x154) > [ 33.186432] [<c016ca28>] (kernfs_fop_write) from [<c01114fc>] > (vfs_write+0xb8/0x170) > [ 33.194147] [<c01114fc>] (vfs_write) from [<c0111a38>] > (SyS_write+0x40/0x80) > [ 33.201154] [<c0111a38>] (SyS_write) from [<c000dce0>] > (ret_fast_syscall+0x0/0x48) > [ 33.209634] _cpu_up: attempt to bring up CPU 5 failed > [ 33.213702] ------------[ cut here ]------------
What sysfs file is being written to here in interrupt context? > > Signed-off-by: Anand Moon <moon.li...@yahoo.com> > --- > fs/kernfs/file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c > index 4429d6d..fa97883 100644 > --- a/fs/kernfs/file.c > +++ b/fs/kernfs/file.c > @@ -278,7 +278,7 @@ static ssize_t kernfs_fop_write(struct file *file, const > char __user *user_buf, > len = min_t(size_t, count, PAGE_SIZE); > } > > - buf = kmalloc(len + 1, GFP_KERNEL); > + buf = kzalloc(len + 1, GFP_ATOMIC); kzalloc makes no sense as we copy right over the data right after this in a copy_from_user() call. Why change it? And, the fact that we can sleep in copy_from_user(), makes this change to GFP_ATOMIC really suspect. We need to find the root cause here... thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
