On 2020-06-30 04:59, Matthew Wilcox wrote: ...
How about ... [ 38.049155] flags: 0x17ffe000000000e(anon|referenced|uptodate|dirty|compound) That is, change pageflag_names[] to print 'head' as 'compound' and move the 'anon' or 'ksm' to look like a pageflag. Also CMA. Like this: +++ b/include/trace/events/mmflags.h @@ -96,7 +96,7 @@ {1UL << PG_private, "private" }, \ {1UL << PG_private_2, "private_2" }, \ {1UL << PG_writeback, "writeback" }, \ - {1UL << PG_head, "head" }, \ + {1UL << PG_head, "compound" }, \ {1UL << PG_mappedtodisk, "mappedtodisk" }, \ {1UL << PG_reclaim, "reclaim" }, \ {1UL << PG_swapbacked, "swapbacked" }, \ +++ b/mm/debug.c @@ -54,7 +54,7 @@ void __dump_page(struct page *page, const char *reason) * state for debugging, it should be fine to accept a bit of * inaccuracy here due to racing. */ - bool page_cma = is_migrate_cma_page(page); + char *cma = is_migrate_cma_page(page) ? "|cma" : ""; int mapcount; char *type = "";@@ -71,6 +71,10 @@ void __dump_page(struct page *page, const char *reason)if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { /* Corrupt page, cannot call page_mapping */ mapping = page->mapping; + if ((unsigned long)mapping & PAGE_MAPPING_ANON) + mapping = NULL; + mapping = (struct address_space *) + ((unsigned long)mapping & ~PAGE_MAPPING_FLAGS); head = page; compound = false; } else { [...] if (PageKsm(page)) - type = "ksm "; + type = "ksm|"; else if (PageAnon(page)) - type = "anon "; - else if (mapping) { + type = "anon|"; + + BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); + pr_warn("flags: %#lx(%s%pGp%s)\n", page->flags, type, &page->flags, + cma); + + if (mapping) { const struct inode *host; const struct address_space_operations *a_ops; @@ -163,11 +167,6 @@ void __dump_page(struct page *page, const char *reason) } } out_mapping: - BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); - - pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags, - page_cma ? " CMA" : ""); - hex_only: print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page, Can also delete the 'out_mapping' label this way.
OK, so after applying that on top of your original series, and your line-break approach, here's what the output looks like for regular and THP, head and tail pages (all involving FOLL_PIN): THP FOLL_PIN page: head page: [ 42.360473] page:0000000025f35fdb refcount:513 mapcount:1 mapping:0000000000000000 index:0x0 [ 42.368012] head:0000000025f35fdb order:9 compound_mapcount:1 compound_pincount:512 [ 42.374761] flags: 0x17ffe000001000e(anon|referenced|uptodate|dirty|compound) [ 42.380994] raw: 017ffe000001000e ffffffff83649ca0 ffffea0020c80008 ffff888898091901 [ 42.387822] raw: 0000000000000000 0000000000000000 00000201ffffffff 0000000000000000 [ 42.394680] page dumped because: gup_benchmark: head page: dump_page test THP FOLL_PIN page: tail page: [ 42.408222] page:00000000803d233b refcount:513 mapcount:1 mapping:0000000000000000 index:0x11 [ 42.415850] head:0000000025f35fdb order:9 compound_mapcount:1 compound_pincount:512 [ 42.422607] flags: 0x17ffe0000000000(anon|) [ 42.425772] raw: 017ffe0000000000 ffffea0020c98001 ffffea0020c98448 dead000000000400 [ 42.432636] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 [ 42.439490] head: 017ffe000001000e ffffffff83649ca0 ffffea0020c80008 ffff888898091901 [ 42.446431] head: 0000000000000000 0000000000000000 00000201ffffffff 0000000000000000 [ 42.453355] page dumped because: gup_benchmark: tail page: dump_page test Non-THP FOLL_PIN page: head page: [ 41.513677] page:00000000190e28ba refcount:1025 mapcount:1 mapping:0000000000000000 index:0x0 [ 41.521331] flags: 0x17ffe0000080034(anon|uptodate|lru|active|swapbacked) [ 41.527189] raw: 017ffe0000080034 ffffea002228db08 ffffea0022215108 ffff888898090191 [ 41.534020] raw: 0000000000000000 0000000000000000 0000040100000000 0000000000000000 [ 41.540863] page dumped because: gup_benchmark: head page: dump_page test Non-THP FOLL_PIN page: tail page: [ 41.554472] page:00000000696a8210 refcount:1025 mapcount:1 mapping:0000000000000000 index:0x11 [ 41.562230] flags: 0x17ffe0000080034(anon|uptodate|lru|active|swapbacked) [ 41.568073] raw: 017ffe0000080034 ffffea0022195688 ffffea0021a4e608 ffff888898090191 [ 41.574940] raw: 0000000000000011 0000000000000000 0000040100000000 0000000000000000 [ 41.581768] page dumped because: gup_benchmark: tail page: dump_page test
(I really like it that we're debating this ... it feels like we've been in a bit of a push-pull with the debug patches over the years)
Yes, it's good that we're pausing a moment to polish this up. Lots of goodness here and I like the above output. thanks, -- John Hubbard NVIDIA
