| From: Shiyang Ruan <ruansy.fnst@fujitsu.com> |
| Subject: fsdax: introduce page->share for fsdax in reflink mode |
| Date: Thu, 1 Dec 2022 15:28:51 +0000 |
| |
| Patch series "fsdax,xfs: fix warning messages", v2. |
| |
| Many testcases failed in dax+reflink mode with warning message in dmesg. |
| Such as generic/051,075,127. The warning message is like this: |
| [ 775.509337] ------------[ cut here ]------------ |
| [ 775.509636] WARNING: CPU: 1 PID: 16815 at fs/dax.c:386 dax_insert_entry.cold+0x2e/0x69 |
| [ 775.510151] Modules linked in: auth_rpcgss oid_registry nfsv4 algif_hash af_alg af_packet nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink ip6table_filter ip6_tables iptable_filter ip_tables x_tables dax_pmem nd_pmem nd_btt sch_fq_codel configfs xfs libcrc32c fuse |
| [ 775.524288] CPU: 1 PID: 16815 Comm: fsx Kdump: loaded Tainted: G W 6.1.0-rc4+ #164 eb34e4ee4200c7cbbb47de2b1892c5a3e027fd6d |
| [ 775.524904] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Arch Linux 1.16.0-3-3 04/01/2014 |
| [ 775.525460] RIP: 0010:dax_insert_entry.cold+0x2e/0x69 |
| [ 775.525797] Code: c7 c7 18 eb e0 81 48 89 4c 24 20 48 89 54 24 10 e8 73 6d ff ff 48 83 7d 18 00 48 8b 54 24 10 48 8b 4c 24 20 0f 84 e3 e9 b9 ff <0f> 0b e9 dc e9 b9 ff 48 c7 c6 a0 20 c3 81 48 c7 c7 f0 ea e0 81 48 |
| [ 775.526708] RSP: 0000:ffffc90001d57b30 EFLAGS: 00010082 |
| [ 775.527042] RAX: 000000000000002a RBX: 0000000000000000 RCX: 0000000000000042 |
| [ 775.527396] RDX: ffffea000a0f6c80 RSI: ffffffff81dfab1b RDI: 00000000ffffffff |
| [ 775.527819] RBP: ffffea000a0f6c40 R08: 0000000000000000 R09: ffffffff820625e0 |
| [ 775.528241] R10: ffffc90001d579d8 R11: ffffffff820d2628 R12: ffff88815fc98320 |
| [ 775.528598] R13: ffffc90001d57c18 R14: 0000000000000000 R15: 0000000000000001 |
| [ 775.528997] FS: 00007f39fc75d740(0000) GS:ffff88817bc80000(0000) knlGS:0000000000000000 |
| [ 775.529474] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| [ 775.529800] CR2: 00007f39fc772040 CR3: 0000000107eb6001 CR4: 00000000003706e0 |
| [ 775.530214] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| [ 775.530592] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| [ 775.531002] Call Trace: |
| [ 775.531230] <TASK> |
| [ 775.531444] dax_fault_iter+0x267/0x6c0 |
| [ 775.531719] dax_iomap_pte_fault+0x198/0x3d0 |
| [ 775.532002] __xfs_filemap_fault+0x24a/0x2d0 [xfs aa8d25411432b306d9554da38096f4ebb86bdfe7] |
| [ 775.532603] __do_fault+0x30/0x1e0 |
| [ 775.532903] do_fault+0x314/0x6c0 |
| [ 775.533166] __handle_mm_fault+0x646/0x1250 |
| [ 775.533480] handle_mm_fault+0xc1/0x230 |
| [ 775.533810] do_user_addr_fault+0x1ac/0x610 |
| [ 775.534110] exc_page_fault+0x63/0x140 |
| [ 775.534389] asm_exc_page_fault+0x22/0x30 |
| [ 775.534678] RIP: 0033:0x7f39fc55820a |
| [ 775.534950] Code: 00 01 00 00 00 74 99 83 f9 c0 0f 87 7b fe ff ff c5 fe 6f 4e 20 48 29 fe 48 83 c7 3f 49 8d 0c 10 48 83 e7 c0 48 01 fe 48 29 f9 <f3> a4 c4 c1 7e 7f 00 c4 c1 7e 7f 48 20 c5 f8 77 c3 0f 1f 44 00 00 |
| [ 775.535839] RSP: 002b:00007ffc66a08118 EFLAGS: 00010202 |
| [ 775.536157] RAX: 00007f39fc772001 RBX: 0000000000042001 RCX: 00000000000063c1 |
| [ 775.536537] RDX: 0000000000006400 RSI: 00007f39fac42050 RDI: 00007f39fc772040 |
| [ 775.536919] RBP: 0000000000006400 R08: 00007f39fc772001 R09: 0000000000042000 |
| [ 775.537304] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001 |
| [ 775.537694] R13: 00007f39fc772000 R14: 0000000000006401 R15: 0000000000000003 |
| [ 775.538086] </TASK> |
| [ 775.538333] ---[ end trace 0000000000000000 ]--- |
| |
| This also affects dax+noreflink mode if we run the test after a |
| dax+reflink test. So, the most urgent thing is solving the warning |
| messages. |
| |
| With these fixes, most warning messages in dax_associate_entry() are gone. |
| But honestly, generic/388 will randomly failed with the warning. The |
| case shutdown the xfs when fsstress is running, and do it for many times. |
| I think the reason is that dax pages in use are not able to be invalidated |
| in time when fs is shutdown. The next time dax page to be associated, it |
| still remains the mapping value set last time. I'll keep on solving it. |
| |
| The warning message in dax_writeback_one() can also be fixed because of |
| the dax unshare. |
| |
| |
| This patch (of 8): |
| |
| fsdax page is used not only when CoW, but also mapread. To make the it |
| easily understood, use 'share' to indicate that the dax page is shared by |
| more than one extent. And add helper functions to use it. |
| |
| Also, the flag needs to be renamed to PAGE_MAPPING_DAX_SHARED. |
| |
| [ruansy.fnst@fujitsu.com: rename several functions] |
| Link: https://lkml.kernel.org/r/1669972991-246-1-git-send-email-ruansy.fnst@fujitsu.com |
| [ruansy.fnst@fujitsu.com: v2.2] |
| Link: https://lkml.kernel.org/r/1670381359-53-1-git-send-email-ruansy.fnst@fujitsu.com |
| Link: https://lkml.kernel.org/r/1669908538-55-1-git-send-email-ruansy.fnst@fujitsu.com |
| Link: https://lkml.kernel.org/r/1669908538-55-2-git-send-email-ruansy.fnst@fujitsu.com |
| Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> |
| Reviewed-by: Allison Henderson <allison.henderson@oracle.com> |
| Reviewed-by: Darrick J. Wong <djwong@kernel.org> |
| Cc: Dan Williams <dan.j.williams@intel.com> |
| Cc: Dave Chinner <david@fromorbit.com> |
| Cc: Jason Gunthorpe <jgg@nvidia.com> |
| Cc: Alistair Popple <apopple@nvidia.com> |
| Cc: John Hubbard <jhubbard@nvidia.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| fs/dax.c | 38 ++++++++++++++++++++--------------- |
| include/linux/mm_types.h | 5 +++- |
| include/linux/page-flags.h | 2 - |
| 3 files changed, 27 insertions(+), 18 deletions(-) |
| |
| --- a/fs/dax.c~fsdax-introduce-page-share-for-fsdax-in-reflink-mode |
| +++ a/fs/dax.c |
| @@ -334,35 +334,41 @@ static unsigned long dax_end_pfn(void *e |
| for (pfn = dax_to_pfn(entry); \ |
| pfn < dax_end_pfn(entry); pfn++) |
| |
| -static inline bool dax_mapping_is_cow(struct address_space *mapping) |
| +static inline bool dax_page_is_shared(struct page *page) |
| { |
| - return (unsigned long)mapping == PAGE_MAPPING_DAX_COW; |
| + return page->mapping == PAGE_MAPPING_DAX_SHARED; |
| } |
| |
| /* |
| - * Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount. |
| + * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the |
| + * refcount. |
| */ |
| -static inline void dax_mapping_set_cow(struct page *page) |
| +static inline void dax_page_share_get(struct page *page) |
| { |
| - if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) { |
| + if (page->mapping != PAGE_MAPPING_DAX_SHARED) { |
| /* |
| * Reset the index if the page was already mapped |
| * regularly before. |
| */ |
| if (page->mapping) |
| - page->index = 1; |
| - page->mapping = (void *)PAGE_MAPPING_DAX_COW; |
| + page->share = 1; |
| + page->mapping = PAGE_MAPPING_DAX_SHARED; |
| } |
| - page->index++; |
| + page->share++; |
| +} |
| + |
| +static inline unsigned long dax_page_share_put(struct page *page) |
| +{ |
| + return --page->share; |
| } |
| |
| /* |
| - * When it is called in dax_insert_entry(), the cow flag will indicate that |
| + * When it is called in dax_insert_entry(), the shared flag will indicate that |
| * whether this entry is shared by multiple files. If so, set the page->mapping |
| - * FS_DAX_MAPPING_COW, and use page->index as refcount. |
| + * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount. |
| */ |
| static void dax_associate_entry(void *entry, struct address_space *mapping, |
| - struct vm_area_struct *vma, unsigned long address, bool cow) |
| + struct vm_area_struct *vma, unsigned long address, bool shared) |
| { |
| unsigned long size = dax_entry_size(entry), pfn, index; |
| int i = 0; |
| @@ -374,8 +380,8 @@ static void dax_associate_entry(void *en |
| for_each_mapped_pfn(entry, pfn) { |
| struct page *page = pfn_to_page(pfn); |
| |
| - if (cow) { |
| - dax_mapping_set_cow(page); |
| + if (shared) { |
| + dax_page_share_get(page); |
| } else { |
| WARN_ON_ONCE(page->mapping); |
| page->mapping = mapping; |
| @@ -396,9 +402,9 @@ static void dax_disassociate_entry(void |
| struct page *page = pfn_to_page(pfn); |
| |
| WARN_ON_ONCE(trunc && page_ref_count(page) > 1); |
| - if (dax_mapping_is_cow(page->mapping)) { |
| - /* keep the CoW flag if this page is still shared */ |
| - if (page->index-- > 0) |
| + if (dax_page_is_shared(page)) { |
| + /* keep the shared flag if this page is still shared */ |
| + if (dax_page_share_put(page) > 0) |
| continue; |
| } else |
| WARN_ON_ONCE(page->mapping && page->mapping != mapping); |
| --- a/include/linux/mm_types.h~fsdax-introduce-page-share-for-fsdax-in-reflink-mode |
| +++ a/include/linux/mm_types.h |
| @@ -104,7 +104,10 @@ struct page { |
| }; |
| /* See page-flags.h for PAGE_MAPPING_FLAGS */ |
| struct address_space *mapping; |
| - pgoff_t index; /* Our offset within mapping. */ |
| + union { |
| + pgoff_t index; /* Our offset within mapping. */ |
| + unsigned long share; /* share count for fsdax */ |
| + }; |
| /** |
| * @private: Mapping-private opaque data. |
| * Usually used for buffer_heads if PagePrivate. |
| --- a/include/linux/page-flags.h~fsdax-introduce-page-share-for-fsdax-in-reflink-mode |
| +++ a/include/linux/page-flags.h |
| @@ -638,7 +638,7 @@ PAGEFLAG_FALSE(VmemmapSelfHosted, vmemma |
| * Different with flags above, this flag is used only for fsdax mode. It |
| * indicates that this page->mapping is now under reflink case. |
| */ |
| -#define PAGE_MAPPING_DAX_COW 0x1 |
| +#define PAGE_MAPPING_DAX_SHARED ((void *)0x1) |
| |
| static __always_inline bool folio_mapping_flags(struct folio *folio) |
| { |
| _ |
