| Message ID | 20211022023052.33114-1-rongwei.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [RESEND] mm, thp: bail out early in collapse_file for writeback page | expand |
Hi, all This patch had sent out with another one at first time. but the other maybe has something to improve. So, I plan to send this patch alone. original link: https://patchwork.kernel.org/project/linux-mm/patch/20211011022241.97072-3-rongwei.wang@linux.alibaba.com/ Thanks! On 10/22/21 10:30 AM, Rongwei Wang wrote: > Currently collapse_file does not explicitly check PG_writeback, instead, > page_has_private and try_to_release_page are used to filter writeback > pages. This does not work for xfs with blocksize equal to or larger > than pagesize, because in such case xfs has no page->private. > > This makes collapse_file bail out early for writeback page. Otherwise, > xfs end_page_writeback will panic as follows. > > page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 > aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" > flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) > raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 > raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 > page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) > page->mem_cgroup:ffff0000c3e9a000 > ------------[ cut here ]------------ > kernel BUG at include/linux/mm.h:1212! > Internal error: Oops - BUG: 0 [#1] SMP > Modules linked in: > BUG: Bad page state in process khugepaged pfn:84ef32 > xfs(E) > page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 > libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... > CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... > pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) > pc : end_page_writeback+0x1c0/0x214 > lr : end_page_writeback+0x1c0/0x214 > sp : ffff800011ce3cc0 > x29: ffff800011ce3cc0 x28: 0000000000000000 > x27: ffff000c04608040 x26: 0000000000000000 > x25: ffff000c04608040 x24: 0000000000001000 > x23: ffff0003f88c8530 x22: 0000000000001000 > x21: ffff0003f88c8530 x20: 0000000000000000 > x19: fffffe00201bcc80 x18: 0000000000000030 > x17: 0000000000000000 x16: 0000000000000000 > x15: ffff000c018f9760 x14: ffffffffffffffff > x13: ffff8000119d72b0 x12: ffff8000119d6ee3 > x11: ffff8000117b69b8 x10: 00000000ffff8000 > x9 : ffff800010617534 x8 : 0000000000000000 > x7 : ffff8000114f69b8 x6 : 000000000000000f > x5 : 0000000000000000 x4 : 0000000000000000 > x3 : 0000000000000400 x2 : 0000000000000000 > x1 : 0000000000000000 x0 : 0000000000000000 > Call trace: > end_page_writeback+0x1c0/0x214 > iomap_finish_page_writeback+0x13c/0x204 > iomap_finish_ioend+0xe8/0x19c > iomap_writepage_end_bio+0x38/0x50 > bio_endio+0x168/0x1ec > blk_update_request+0x278/0x3f0 > blk_mq_end_request+0x34/0x15c > virtblk_request_done+0x38/0x74 [virtio_blk] > blk_done_softirq+0xc4/0x110 > __do_softirq+0x128/0x38c > __irq_exit_rcu+0x118/0x150 > irq_exit+0x1c/0x30 > __handle_domain_irq+0x8c/0xf0 > gic_handle_irq+0x84/0x108 > el1_irq+0xcc/0x180 > arch_cpu_idle+0x18/0x40 > default_idle_call+0x4c/0x1a0 > cpuidle_idle_call+0x168/0x1e0 > do_idle+0xb4/0x104 > cpu_startup_entry+0x30/0x9c > secondary_start_kernel+0x104/0x180 > Code: d4210000 b0006161 910c8021 94013f4d (d4210000) > ---[ end trace 4a88c6a074082f8c ]--- > Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt > > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > Suggested-by: Yang Shi <shy828301@gmail.com> > Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> > Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com> > Cc: <stable@vger.kernel.org> > Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Reviewed-by: Yang Shi <shy828301@gmail.com> > --- > mm/khugepaged.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 045cc579f724..48de4e1b0783 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1763,6 +1763,10 @@ static void collapse_file(struct mm_struct *mm, > filemap_flush(mapping); > result = SCAN_FAIL; > goto xa_unlocked; > + } else if (PageWriteback(page)) { > + xas_unlock_irq(&xas); > + result = SCAN_FAIL; > + goto xa_unlocked; > } else if (trylock_page(page)) { > get_page(page); > xas_unlock_irq(&xas); > @@ -1798,7 +1802,8 @@ static void collapse_file(struct mm_struct *mm, > goto out_unlock; > } > > - if (!is_shmem && PageDirty(page)) { > + if (!is_shmem && (PageDirty(page) || > + PageWriteback(page))) { > /* > * khugepaged only works on read-only fd, so this > * page is dirty because it hasn't been flushed >
On Fri, Oct 22, 2021 at 10:30:52AM +0800, Rongwei Wang wrote: > Currently collapse_file does not explicitly check PG_writeback, instead, > page_has_private and try_to_release_page are used to filter writeback > pages. This does not work for xfs with blocksize equal to or larger > than pagesize, because in such case xfs has no page->private. > > This makes collapse_file bail out early for writeback page. Otherwise, > xfs end_page_writeback will panic as follows. > > page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 > aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" > flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) > raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 > raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 > page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) > page->mem_cgroup:ffff0000c3e9a000 > ------------[ cut here ]------------ > kernel BUG at include/linux/mm.h:1212! > Internal error: Oops - BUG: 0 [#1] SMP > Modules linked in: > BUG: Bad page state in process khugepaged pfn:84ef32 > xfs(E) > page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 > libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... > CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... > pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) > pc : end_page_writeback+0x1c0/0x214 > lr : end_page_writeback+0x1c0/0x214 > sp : ffff800011ce3cc0 > x29: ffff800011ce3cc0 x28: 0000000000000000 > x27: ffff000c04608040 x26: 0000000000000000 > x25: ffff000c04608040 x24: 0000000000001000 > x23: ffff0003f88c8530 x22: 0000000000001000 > x21: ffff0003f88c8530 x20: 0000000000000000 > x19: fffffe00201bcc80 x18: 0000000000000030 > x17: 0000000000000000 x16: 0000000000000000 > x15: ffff000c018f9760 x14: ffffffffffffffff > x13: ffff8000119d72b0 x12: ffff8000119d6ee3 > x11: ffff8000117b69b8 x10: 00000000ffff8000 > x9 : ffff800010617534 x8 : 0000000000000000 > x7 : ffff8000114f69b8 x6 : 000000000000000f > x5 : 0000000000000000 x4 : 0000000000000000 > x3 : 0000000000000400 x2 : 0000000000000000 > x1 : 0000000000000000 x0 : 0000000000000000 > Call trace: > end_page_writeback+0x1c0/0x214 > iomap_finish_page_writeback+0x13c/0x204 > iomap_finish_ioend+0xe8/0x19c > iomap_writepage_end_bio+0x38/0x50 > bio_endio+0x168/0x1ec > blk_update_request+0x278/0x3f0 > blk_mq_end_request+0x34/0x15c > virtblk_request_done+0x38/0x74 [virtio_blk] > blk_done_softirq+0xc4/0x110 > __do_softirq+0x128/0x38c > __irq_exit_rcu+0x118/0x150 > irq_exit+0x1c/0x30 > __handle_domain_irq+0x8c/0xf0 > gic_handle_irq+0x84/0x108 > el1_irq+0xcc/0x180 > arch_cpu_idle+0x18/0x40 > default_idle_call+0x4c/0x1a0 > cpuidle_idle_call+0x168/0x1e0 > do_idle+0xb4/0x104 > cpu_startup_entry+0x30/0x9c > secondary_start_kernel+0x104/0x180 > Code: d4210000 b0006161 910c8021 94013f4d (d4210000) > ---[ end trace 4a88c6a074082f8c ]--- > Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt > > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > Suggested-by: Yang Shi <shy828301@gmail.com> > Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> > Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com> > Cc: <stable@vger.kernel.org> > Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Reviewed-by: Yang Shi <shy828301@gmail.com> Okay, it makes sense: Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> I would also add a sentance in the commit message that PG_writeback setting is serialized with page_lock(). I have not had experience with writeback and it was something that I had to dig up. > --- > mm/khugepaged.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 045cc579f724..48de4e1b0783 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1763,6 +1763,10 @@ static void collapse_file(struct mm_struct *mm, > filemap_flush(mapping); > result = SCAN_FAIL; > goto xa_unlocked; > + } else if (PageWriteback(page)) { > + xas_unlock_irq(&xas); > + result = SCAN_FAIL; > + goto xa_unlocked; > } else if (trylock_page(page)) { > get_page(page); > xas_unlock_irq(&xas); > @@ -1798,7 +1802,8 @@ static void collapse_file(struct mm_struct *mm, > goto out_unlock; > } > > - if (!is_shmem && PageDirty(page)) { > + if (!is_shmem && (PageDirty(page) || > + PageWriteback(page))) { > /* > * khugepaged only works on read-only fd, so this > * page is dirty because it hasn't been flushed > -- > 2.27.0 > >
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 045cc579f724..48de4e1b0783 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1763,6 +1763,10 @@ static void collapse_file(struct mm_struct *mm, filemap_flush(mapping); result = SCAN_FAIL; goto xa_unlocked; + } else if (PageWriteback(page)) { + xas_unlock_irq(&xas); + result = SCAN_FAIL; + goto xa_unlocked; } else if (trylock_page(page)) { get_page(page); xas_unlock_irq(&xas); @@ -1798,7 +1802,8 @@ static void collapse_file(struct mm_struct *mm, goto out_unlock; } - if (!is_shmem && PageDirty(page)) { + if (!is_shmem && (PageDirty(page) || + PageWriteback(page))) { /* * khugepaged only works on read-only fd, so this * page is dirty because it hasn't been flushed
Currently collapse_file does not explicitly check PG_writeback, instead, page_has_private and try_to_release_page are used to filter writeback pages. This does not work for xfs with blocksize equal to or larger than pagesize, because in such case xfs has no page->private. This makes collapse_file bail out early for writeback page. Otherwise, xfs end_page_writeback will panic as follows. page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) page->mem_cgroup:ffff0000c3e9a000 ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:1212! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: BUG: Bad page state in process khugepaged pfn:84ef32 xfs(E) page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) pc : end_page_writeback+0x1c0/0x214 lr : end_page_writeback+0x1c0/0x214 sp : ffff800011ce3cc0 x29: ffff800011ce3cc0 x28: 0000000000000000 x27: ffff000c04608040 x26: 0000000000000000 x25: ffff000c04608040 x24: 0000000000001000 x23: ffff0003f88c8530 x22: 0000000000001000 x21: ffff0003f88c8530 x20: 0000000000000000 x19: fffffe00201bcc80 x18: 0000000000000030 x17: 0000000000000000 x16: 0000000000000000 x15: ffff000c018f9760 x14: ffffffffffffffff x13: ffff8000119d72b0 x12: ffff8000119d6ee3 x11: ffff8000117b69b8 x10: 00000000ffff8000 x9 : ffff800010617534 x8 : 0000000000000000 x7 : ffff8000114f69b8 x6 : 000000000000000f x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000400 x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000 Call trace: end_page_writeback+0x1c0/0x214 iomap_finish_page_writeback+0x13c/0x204 iomap_finish_ioend+0xe8/0x19c iomap_writepage_end_bio+0x38/0x50 bio_endio+0x168/0x1ec blk_update_request+0x278/0x3f0 blk_mq_end_request+0x34/0x15c virtblk_request_done+0x38/0x74 [virtio_blk] blk_done_softirq+0xc4/0x110 __do_softirq+0x128/0x38c __irq_exit_rcu+0x118/0x150 irq_exit+0x1c/0x30 __handle_domain_irq+0x8c/0xf0 gic_handle_irq+0x84/0x108 el1_irq+0xcc/0x180 arch_cpu_idle+0x18/0x40 default_idle_call+0x4c/0x1a0 cpuidle_idle_call+0x168/0x1e0 do_idle+0xb4/0x104 cpu_startup_entry+0x30/0x9c secondary_start_kernel+0x104/0x180 Code: d4210000 b0006161 910c8021 94013f4d (d4210000) ---[ end trace 4a88c6a074082f8c ]--- Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Suggested-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Xu Yu <xuyu@linux.alibaba.com> Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com> Cc: <stable@vger.kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Yang Shi <shy828301@gmail.com> --- mm/khugepaged.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)