On Fri 16-12-16 11:38:11, Brian Foster wrote:
> On Thu, Dec 15, 2016 at 03:07:11PM +0100, Michal Hocko wrote:
[...]
> > @@ -459,7 +459,7 @@ _xfs_buf_map_pages(
> > break;
> > vm_unmap_aliases();
> > } while (retried++ <= 1);
> > - memalloc_noio_restore(noio_flag);
> > + memalloc_noio_restore(nofs_flag);
>
> memalloc_nofs_restore() ?
Ups, you are right of course. Fixed.
---
>From 47826112e59014030ffe27a673c1b1de345dd9de Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Thu, 15 Dec 2016 13:10:53 +0100
Subject: [PATCH] xfs: use memalloc_nofs_{save,restore} instead of
memalloc_noio*
kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
API to prevent from reclaim recursion into the fs because vmalloc can
invoke unconditional GFP_KERNEL allocations and these functions might be
called from the NOFS contexts. The memalloc_noio_save will enforce
GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
unnecessary. Let's use memalloc_nofs_{save,restore} instead as it should
provide exactly what we need here - implicit GFP_NOFS context.
Changes since v1
- s@memalloc_noio_restore@memalloc_nofs_restore@ in _xfs_buf_map_pages
as per Brian Foster
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
fs/xfs/kmem.c | 10 +++++-----
fs/xfs/xfs_buf.c | 8 ++++----
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
index a76a05dae96b..d69ed5e76621 100644
--- a/fs/xfs/kmem.c
+++ b/fs/xfs/kmem.c
@@ -65,7 +65,7 @@ kmem_alloc(size_t size, xfs_km_flags_t flags)
void *
kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
{
- unsigned noio_flag = 0;
+ unsigned nofs_flag = 0;
void *ptr;
gfp_t lflags;
@@ -80,14 +80,14 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
* context via PF_MEMALLOC_NOIO to prevent memory reclaim re-entering
* the filesystem here and potentially deadlocking.
*/
- if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
- noio_flag = memalloc_noio_save();
+ if (flags & KM_NOFS)
+ nofs_flag = memalloc_nofs_save();
lflags = kmem_flags_convert(flags);
ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
- if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
- memalloc_noio_restore(noio_flag);
+ if (flags & KM_NOFS)
+ memalloc_nofs_restore(nofs_flag);
return ptr;
}
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index f31ae592dcae..e9eec256056c 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -441,17 +441,17 @@ _xfs_buf_map_pages(
bp->b_addr = NULL;
} else {
int retried = 0;
- unsigned noio_flag;
+ unsigned nofs_flag;
/*
* vm_map_ram() will allocate auxillary structures (e.g.
* pagetables) with GFP_KERNEL, yet we are likely to be under
* GFP_NOFS context here. Hence we need to tell memory reclaim
- * that we are in such a context via PF_MEMALLOC_NOIO to prevent
+ * that we are in such a context via PF_MEMALLOC_NOFS to prevent
* memory reclaim re-entering the filesystem here and
* potentially deadlocking.
*/
- noio_flag = memalloc_noio_save();
+ nofs_flag = memalloc_nofs_save();
do {
bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
-1, PAGE_KERNEL);
@@ -459,7 +459,7 @@ _xfs_buf_map_pages(
break;
vm_unmap_aliases();
} while (retried++ <= 1);
- memalloc_noio_restore(noio_flag);
+ memalloc_nofs_restore(nofs_flag);
if (!bp->b_addr)
return -ENOMEM;
--
2.10.2
--
Michal Hocko
SUSE Labs
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