On Tue, May 07, 2019 at 02:50:05AM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: baf76f0c slip: make slhc_free() silently accept an error p.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16dbe6cca00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a42d110b47dd6b36 > dashboard link: https://syzkaller.appspot.com/bug?extid=d84c80f9fe26a0f7a734 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > How reproducible is it and can the following (compile tested only) patch be tested please? I'm thinking it's a similar class of bug to 6b0868c820ff ("mm/compaction.c: correct zone boundary handling when resetting pageblock skip hints") diff --git a/mm/compaction.c b/mm/compaction.c index 3319e0872d01..ae4d99d31b61 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1228,7 +1228,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long /* Pageblock boundaries */ start_pfn = pageblock_start_pfn(pfn); - end_pfn = min(start_pfn + pageblock_nr_pages, zone_end_pfn(cc->zone)); + end_pfn = min(start_pfn + pageblock_nr_pages, zone_end_pfn(cc->zone) - 1); /* Scan before */ if (start_pfn != pfn) { @@ -1239,7 +1239,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long /* Scan after */ start_pfn = pfn + nr_isolated; - if (start_pfn != end_pfn) + if (start_pfn < end_pfn) isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); /* Skip this pageblock in the future as it's full or nearly full */
