On Wed, Nov 30 2016, Robin H. Johnson wrote: > (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]>
Acked-by: Michal Nazarewicz <[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); I’m thinking out loud here, but maybe it would be useful to include a count of how many times this message has been suppressed? > + dump_stack(); Perhaps do it only if CMA_DEBUG? + if (IS_ENABLED(CONFIG_CMA_DEBUG)) + 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 -- Best regards ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ «If at first you don’t succeed, give up skydiving»
