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Date: Fri, 5 Dec 2014 10:23:02 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH 3/3 v2] f2fs: call radix_tree_preload before
radix_tree_insert
Change log from v1:
o remain GFP_ATOMIC for free_nid list due to its spin_lock
>From 769ec6e5b7d4a8115447736871be8bffaaba3a7d Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@...nel.org>
Date: Wed, 3 Dec 2014 20:47:26 -0800
Subject: [PATCH] f2fs: call radix_tree_preload before radix_tree_insert
This patch tries to fix:
BUG: using smp_processor_id() in preemptible [00000000] code: f2fs_gc-254:0/384
(radix_tree_node_alloc+0x14/0x74) from [<c033d8a0>] (radix_tree_insert+0x110/0x200)
(radix_tree_insert+0x110/0x200) from [<c02e8264>] (gc_data_segment+0x340/0x52c)
(gc_data_segment+0x340/0x52c) from [<c02e8658>] (f2fs_gc+0x208/0x400)
(f2fs_gc+0x208/0x400) from [<c02e8a98>] (gc_thread_func+0x248/0x28c)
(gc_thread_func+0x248/0x28c) from [<c0139944>] (kthread+0xa0/0xac)
(kthread+0xa0/0xac) from [<c0105ef8>] (ret_from_fork+0x14/0x3c)
The reason is that f2fs calls radix_tree_insert under enabled preemption.
So, before calling it, we need to call radix_tree_preload.
Otherwise, we should use _GFP_WAIT for the radix tree, and use mutex or
semaphore to cover the radix tree operations.
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
fs/f2fs/checkpoint.c | 8 ++++++++
fs/f2fs/gc.c | 6 ++----
fs/f2fs/node.c | 11 +++++++++--
3 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 20a917b..6a81b73 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -304,6 +304,11 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
struct inode_management *im = &sbi->im[type];
struct ino_entry *e;
retry:
+ if (radix_tree_preload(GFP_NOFS)) {
+ cond_resched();
+ goto retry;
+ }
+
spin_lock(&im->ino_lock);
e = radix_tree_lookup(&im->ino_root, ino);
@@ -311,11 +316,13 @@ retry:
e = kmem_cache_alloc(ino_entry_slab, GFP_ATOMIC);
if (!e) {
spin_unlock(&im->ino_lock);
+ radix_tree_preload_end();
goto retry;
}
if (radix_tree_insert(&im->ino_root, ino, e)) {
spin_unlock(&im->ino_lock);
kmem_cache_free(ino_entry_slab, e);
+ radix_tree_preload_end();
goto retry;
}
memset(e, 0, sizeof(struct ino_entry));
@@ -326,6 +333,7 @@ retry:
im->ino_num++;
}
spin_unlock(&im->ino_lock);
+ radix_tree_preload_end();
}
static void __remove_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index a1af74f..2c58c58 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -351,7 +351,6 @@ static struct inode *find_gc_inode(struct gc_inode_list *gc_list, nid_t ino)
static void add_gc_inode(struct gc_inode_list *gc_list, struct inode *inode)
{
struct inode_entry *new_ie;
- int ret;
if (inode == find_gc_inode(gc_list, inode->i_ino)) {
iput(inode);
@@ -361,8 +360,7 @@ retry:
new_ie = f2fs_kmem_cache_alloc(winode_slab, GFP_NOFS);
new_ie->inode = inode;
- ret = radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie);
- if (ret) {
+ if (radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie)) {
kmem_cache_free(winode_slab, new_ie);
goto retry;
}
@@ -703,7 +701,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi)
struct cp_control cpc;
struct gc_inode_list gc_list = {
.ilist = LIST_HEAD_INIT(gc_list.ilist),
- .iroot = RADIX_TREE_INIT(GFP_ATOMIC),
+ .iroot = RADIX_TREE_INIT(GFP_NOFS),
};
cpc.reason = test_opt(sbi, FASTBOOT) ? CP_UMOUNT : CP_SYNC;
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b47555f..8de4f55 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1447,15 +1447,22 @@ static int add_free_nid(struct f2fs_sb_info *sbi, nid_t nid, bool build)
i->nid = nid;
i->state = NID_NEW;
+ if (radix_tree_preload(GFP_NOFS)) {
+ kmem_cache_free(free_nid_slab, i);
+ return 0;
+ }
+
spin_lock(&nm_i->free_nid_list_lock);
if (radix_tree_insert(&nm_i->free_nid_root, i->nid, i)) {
spin_unlock(&nm_i->free_nid_list_lock);
+ radix_tree_preload_end();
kmem_cache_free(free_nid_slab, i);
return 0;
}
list_add_tail(&i->list, &nm_i->free_nid_list);
nm_i->fcnt++;
spin_unlock(&nm_i->free_nid_list_lock);
+ radix_tree_preload_end();
return 1;
}
@@ -1994,8 +2001,8 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
INIT_RADIX_TREE(&nm_i->free_nid_root, GFP_ATOMIC);
INIT_LIST_HEAD(&nm_i->free_nid_list);
- INIT_RADIX_TREE(&nm_i->nat_root, GFP_ATOMIC);
- INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_ATOMIC);
+ INIT_RADIX_TREE(&nm_i->nat_root, GFP_NOIO);
+ INIT_RADIX_TREE(&nm_i->nat_set_root, GFP_NOIO);
INIT_LIST_HEAD(&nm_i->nat_entries);
mutex_init(&nm_i->build_lock);
--
2.1.1
--
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