| Message ID | 20190412152659.3916-1-cai@lca.pw (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mm/hotplug: treat CMA pages as unmovable | expand |
On Fri 12-04-19 11:26:59, Qian Cai wrote: [...] > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d96ca5bc555b..a9d2b0236167 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8005,7 +8005,10 @@ void *__init alloc_large_system_hash(const char *tablename, > bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > int migratetype, int flags) > { > - unsigned long pfn, iter, found; > + unsigned long found; > + unsigned long iter = 0; > + unsigned long pfn = page_to_pfn(page); > + char reason[] = "unmovable page"; const char *reason = "unovable page"; > > /* > * TODO we could make this much more efficient by not checking every > @@ -8015,17 +8018,20 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > * can still lead to having bootmem allocations in zone_movable. > */ > > - /* > - * CMA allocations (alloc_contig_range) really need to mark isolate > - * CMA pageblocks even when they are not movable in fact so consider > - * them movable here. > - */ > - if (is_migrate_cma(migratetype) && > - is_migrate_cma(get_pageblock_migratetype(page))) > - return false; > + if (is_migrate_cma(get_pageblock_migratetype(page))) { > + /* > + * CMA allocations (alloc_contig_range) really need to mark > + * isolate CMA pageblocks even when they are not movable in fact > + * so consider them movable here. > + */ > + if (is_migrate_cma(migratetype)) > + return false; > + > + strscpy(reason, "CMA page", 9); reason = "CMA page"; > + goto unmovable; > + } Other than that looks good. After fixing the above, feel free to add Acked-by: Michal Hocko <mhocko@suse.com>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d96ca5bc555b..a9d2b0236167 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8005,7 +8005,10 @@ void *__init alloc_large_system_hash(const char *tablename, bool has_unmovable_pages(struct zone *zone, struct page *page, int count, int migratetype, int flags) { - unsigned long pfn, iter, found; + unsigned long found; + unsigned long iter = 0; + unsigned long pfn = page_to_pfn(page); + char reason[] = "unmovable page"; /* * TODO we could make this much more efficient by not checking every @@ -8015,17 +8018,20 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, * can still lead to having bootmem allocations in zone_movable. */ - /* - * CMA allocations (alloc_contig_range) really need to mark isolate - * CMA pageblocks even when they are not movable in fact so consider - * them movable here. - */ - if (is_migrate_cma(migratetype) && - is_migrate_cma(get_pageblock_migratetype(page))) - return false; + if (is_migrate_cma(get_pageblock_migratetype(page))) { + /* + * CMA allocations (alloc_contig_range) really need to mark + * isolate CMA pageblocks even when they are not movable in fact + * so consider them movable here. + */ + if (is_migrate_cma(migratetype)) + return false; + + strscpy(reason, "CMA page", 9); + goto unmovable; + } - pfn = page_to_pfn(page); - for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) { + for (found = 0; iter < pageblock_nr_pages; iter++) { unsigned long check = pfn + iter; if (!pfn_valid_within(check)) @@ -8105,7 +8111,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, unmovable: WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); if (flags & REPORT_FAILURE) - dump_page(pfn_to_page(pfn+iter), "unmovable page"); + dump_page(pfn_to_page(pfn+iter), reason); return true; }
has_unmovable_pages() is used by allocating CMA and gigantic pages as well as the memory hotplug. The later doesn't know how to offline CMA pool properly now, but if an unused (free) CMA page is encountered, then has_unmovable_pages() happily considers it as a free memory and propagates this up the call chain. Memory offlining code then frees the page without a proper CMA tear down which leads to an accounting issues. Moreover if the same memory range is onlined again then the memory never gets back to the CMA pool. State after memory offline: # grep cma /proc/vmstat nr_free_cma 205824 # cat /sys/kernel/debug/cma/cma-kvm_cma/count 209920 Also, kmemleak still think those memory address are reserved but have already been used by the buddy allocator after onlining. Offlined Pages 4096 kmemleak: Cannot insert 0xc000201f7d040008 into the object search tree (overlaps existing) Call Trace: [c00000003dc2faf0] [c000000000884b2c] dump_stack+0xb0/0xf4 (unreliable) [c00000003dc2fb30] [c000000000424fb4] create_object+0x344/0x380 [c00000003dc2fbf0] [c0000000003d178c] __kmalloc_node+0x3ec/0x860 [c00000003dc2fc90] [c000000000319078] kvmalloc_node+0x58/0x110 [c00000003dc2fcd0] [c000000000484d9c] seq_read+0x41c/0x620 [c00000003dc2fd60] [c0000000004472bc] __vfs_read+0x3c/0x70 [c00000003dc2fd80] [c0000000004473ac] vfs_read+0xbc/0x1a0 [c00000003dc2fdd0] [c00000000044783c] ksys_read+0x7c/0x140 [c00000003dc2fe20] [c00000000000b108] system_call+0x5c/0x70 kmemleak: Kernel memory leak detector disabled kmemleak: Object 0xc000201cc8000000 (size 13757317120): kmemleak: comm "swapper/0", pid 0, jiffies 4294937297 kmemleak: min_count = -1 kmemleak: count = 0 kmemleak: flags = 0x5 kmemleak: checksum = 0 kmemleak: backtrace: cma_declare_contiguous+0x2a4/0x3b0 kvm_cma_reserve+0x11c/0x134 setup_arch+0x300/0x3f8 start_kernel+0x9c/0x6e8 start_here_common+0x1c/0x4b0 kmemleak: Automatic memory scanning thread ended Signed-off-by: Qian Cai <cai@lca.pw> --- v2: Borrow some commit log texts from Michal. Call dump_page() in the error path per Michal. mm/page_alloc.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)