(I'm going to respond directly to this email with the stack trace.) On Wed, Nov 30, 2016 at 02:28:49PM +0100, Michal Hocko wrote: > > On the other hand, if this didn’t happen and now happens all the time, > > this indicates a regression in CMA’s capability to allocate pages so > > just rate limiting the output would hide the potential actual issue. > > Or there might be just a much larger demand on those large blocks, no? > But seriously, dumping those message again and again into the low (see > the 2.5_GB_/h to the log is just insane. So there really should be some > throttling. > > Does the following help you Robin. At least to not get swamped by those > message. Here's what I whipped up based on that, to ensure that dump_stack got rate-limited at the same pass as PFNs-busy. It dropped the dmesg spew to ~25MB/hour (and is suppressing ~43 entries/second right now).
commit 6ad4037e18ec2199f8755274d8a745a9904241a1 Author: Robin H. Johnson <[email protected]> Date: Wed Nov 30 10:32:57 2016 -0800 mm: ratelimit & trace PFNs busy. Signed-off-by: Robin H. Johnson <[email protected]> diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6de9440e3ae2..3c28ec3d18f8 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7289,8 +7289,15 @@ int alloc_contig_range(unsigned long start, unsigned long end, /* Make sure the range is really isolated. */ if (test_pages_isolated(outer_start, end, false)) { - pr_info("%s: [%lx, %lx) PFNs busy\n", - __func__, outer_start, end); + static DEFINE_RATELIMIT_STATE(ratelimit_pfn_busy, + DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + if (__ratelimit(&ratelimit_pfn_busy)) { + pr_info("%s: [%lx, %lx) PFNs busy\n", + __func__, outer_start, end); + dump_stack(); + } + ret = -EBUSY; goto done; } -- Robin Hugh Johnson Gentoo Linux: Dev, Infra Lead, Foundation Trustee & Treasurer E-Mail : [email protected] GnuPG FP : 11ACBA4F 4778E3F6 E4EDF38E B27B944E 34884E85 GnuPG FP : 7D0B3CEB E9B85B1F 825BCECF EE05E6F6 A48F6136
