Gaah, my mailer autocompleted Jens' email with an old one.. Sorry for the repeat email with the correct address.
On Thu, Sep 17, 2015 at 11:04 PM, Linus Torvalds <torva...@linux-foundation.org> wrote: > On Thu, Sep 17, 2015 at 10:40 PM, Dave Chinner <da...@fromorbit.com> wrote: >> >> PS: just hit another "did this just get broken in 4.3-rc1" issue - I >> can't run blktrace while there's a IO load because: >> >> $ sudo blktrace -d /dev/vdc >> BLKTRACESETUP(2) /dev/vdc failed: 5/Input/output error >> Thread 1 failed open /sys/kernel/debug/block/(null)/trace1: 2/No such file >> or directory >> .... >> >> [ 641.424618] blktrace: page allocation failure: order:5, mode:0x2040d0 >> [ 641.438933] [<ffffffff811c1569>] kmem_cache_alloc_trace+0x129/0x400 >> [ 641.440240] [<ffffffff811424f8>] relay_open+0x68/0x2c0 >> [ 641.441299] [<ffffffff8115deb1>] do_blk_trace_setup+0x191/0x2d0 >> >> gdb) l *(relay_open+0x68) >> 0xffffffff811424f8 is in relay_open (kernel/relay.c:582). >> 577 return NULL; >> 578 if (subbuf_size > UINT_MAX / n_subbufs) >> 579 return NULL; >> 580 >> 581 chan = kzalloc(sizeof(struct rchan), GFP_KERNEL); >> 582 if (!chan) >> 583 return NULL; >> 584 >> 585 chan->version = RELAYFS_CHANNEL_VERSION; >> 586 chan->n_subbufs = n_subbufs; >> >> and struct rchan has a member struct rchan_buf *buf[NR_CPUS]; >> and CONFIG_NR_CPUS=8192, hence the attempt at an order 5 allocation >> that fails here.... > > Hm. Have you always had MAX_SMP (and the NR_CPU==8192 that it causes)? > From a quick check, none of this code seems to be new. > > That said, having that > > struct rchan_buf *buf[NR_CPUS]; > > in "struct rchan" really is something we should fix. We really should > strive to not allocate things by CONFIG_NR_CPU's, but by the actual > real CPU count. > > This looks to be mostly Jens' code, and much of it harkens back to 2006. Jens? > > Linus -- 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/
