From: Mike Galbraith <efault@gmx.de>
Date: Fri, 3 Jul 2009 08:44:12 -0500
Subject: fs: ntfs: disable interrupt only on !RT
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.6/older/patches-4.6.2-rt5.tar.xz

On Sat, 2007-10-27 at 11:44 +0200, Ingo Molnar wrote:
> * Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>
> > > [10138.175796]  [<c0105de3>] show_trace+0x12/0x14
> > > [10138.180291]  [<c0105dfb>] dump_stack+0x16/0x18
> > > [10138.184769]  [<c011609f>] native_smp_call_function_mask+0x138/0x13d
> > > [10138.191117]  [<c0117606>] smp_call_function+0x1e/0x24
> > > [10138.196210]  [<c012f85c>] on_each_cpu+0x25/0x50
> > > [10138.200807]  [<c0115c74>] flush_tlb_all+0x1e/0x20
> > > [10138.205553]  [<c016caaf>] kmap_high+0x1b6/0x417
> > > [10138.210118]  [<c011ec88>] kmap+0x4d/0x4f
> > > [10138.214102]  [<c026a9d8>] ntfs_end_buffer_async_read+0x228/0x2f9
> > > [10138.220163]  [<c01a0e9e>] end_bio_bh_io_sync+0x26/0x3f
> > > [10138.225352]  [<c01a2b09>] bio_endio+0x42/0x6d
> > > [10138.229769]  [<c02c2a08>] __end_that_request_first+0x115/0x4ac
> > > [10138.235682]  [<c02c2da7>] end_that_request_chunk+0x8/0xa
> > > [10138.241052]  [<c0365943>] ide_end_request+0x55/0x10a
> > > [10138.246058]  [<c036dae3>] ide_dma_intr+0x6f/0xac
> > > [10138.250727]  [<c0366d83>] ide_intr+0x93/0x1e0
> > > [10138.255125]  [<c015afb4>] handle_IRQ_event+0x5c/0xc9
> >
> > Looks like ntfs is kmap()ing from interrupt context. Should be using
> > kmap_atomic instead, I think.
>
> it's not atomic interrupt context but irq thread context - and -rt
> remaps kmap_atomic() to kmap() internally.

Hm.  Looking at the change to mm/bounce.c, perhaps I should do this
instead?

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 fs/ntfs/aops.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -92,13 +92,13 @@ static void ntfs_end_buffer_async_read(s
 			ofs = 0;
 			if (file_ofs < init_size)
 				ofs = init_size - file_ofs;
-			local_irq_save(flags);
+			local_irq_save_nort(flags);
 			kaddr = kmap_atomic(page);
 			memset(kaddr + bh_offset(bh) + ofs, 0,
 					bh->b_size - ofs);
 			flush_dcache_page(page);
 			kunmap_atomic(kaddr);
-			local_irq_restore(flags);
+			local_irq_restore_nort(flags);
 		}
 	} else {
 		clear_buffer_uptodate(bh);
@@ -143,13 +143,13 @@ static void ntfs_end_buffer_async_read(s
 		recs = PAGE_SIZE / rec_size;
 		/* Should have been verified before we got here... */
 		BUG_ON(!recs);
-		local_irq_save(flags);
+		local_irq_save_nort(flags);
 		kaddr = kmap_atomic(page);
 		for (i = 0; i < recs; i++)
 			post_read_mst_fixup((NTFS_RECORD*)(kaddr +
 					i * rec_size), rec_size);
 		kunmap_atomic(kaddr);
-		local_irq_restore(flags);
+		local_irq_restore_nort(flags);
 		flush_dcache_page(page);
 		if (likely(page_uptodate && !PageError(page)))
 			SetPageUptodate(page);
