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authorMatthew L. Creech <mlcreech@gmail.com>2011-03-04 17:55:02 -0500
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2011-03-11 10:52:07 +0200
commitd882962f6af2b484b62a7fb05ef959e1bf355fc4 (patch)
tree040a303908493e5edca3fe5c7aeecab2912bd3b0 /fs/ubifs/journal.c
parent2765df7da540687c4d57ca840182122f074c5b9c (diff)
downloadop-kernel-dev-d882962f6af2b484b62a7fb05ef959e1bf355fc4.zip
op-kernel-dev-d882962f6af2b484b62a7fb05ef959e1bf355fc4.tar.gz
UBIFS: handle allocation failures in UBIFS write path
Running kernel 2.6.37, my PPC-based device occasionally gets an order-2 allocation failure in UBIFS, which causes the root FS to become unwritable: kswapd0: page allocation failure. order:2, mode:0x4050 Call Trace: [c787dc30] [c00085b8] show_stack+0x7c/0x194 (unreliable) [c787dc70] [c0061aec] __alloc_pages_nodemask+0x4f0/0x57c [c787dd00] [c0061b98] __get_free_pages+0x20/0x50 [c787dd10] [c00e4f88] ubifs_jnl_write_data+0x54/0x200 [c787dd50] [c00e82d4] do_writepage+0x94/0x198 [c787dd90] [c00675e4] shrink_page_list+0x40c/0x77c [c787de40] [c0067de0] shrink_inactive_list+0x1e0/0x370 [c787de90] [c0068224] shrink_zone+0x2b4/0x2b8 [c787df00] [c0068854] kswapd+0x408/0x5d4 [c787dfb0] [c0037bcc] kthread+0x80/0x84 [c787dff0] [c000ef44] kernel_thread+0x4c/0x68 Similar problems were encountered last April by Tomasz Stanislawski: http://patchwork.ozlabs.org/patch/50965/ This patch implements Artem's suggested fix: fall back to a mutex-protected static buffer, allocated at mount time. I tested it by forcing execution down the failure path, and didn't see any ill effects. Artem: massaged the patch a little, improved it so that we'd not allocate the write reserve buffer when we are in R/O mode. Signed-off-by: Matthew L. Creech <mlcreech@gmail.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'fs/ubifs/journal.c')
-rw-r--r--fs/ubifs/journal.c28
1 files changed, 22 insertions, 6 deletions
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 914f1bd..aed25e8 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -690,7 +690,7 @@ int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
{
struct ubifs_data_node *data;
int err, lnum, offs, compr_type, out_len;
- int dlen = UBIFS_DATA_NODE_SZ + UBIFS_BLOCK_SIZE * WORST_COMPR_FACTOR;
+ int dlen = COMPRESSED_DATA_NODE_BUF_SZ, allocated = 1;
struct ubifs_inode *ui = ubifs_inode(inode);
dbg_jnl("ino %lu, blk %u, len %d, key %s",
@@ -698,9 +698,19 @@ int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
DBGKEY(key));
ubifs_assert(len <= UBIFS_BLOCK_SIZE);
- data = kmalloc(dlen, GFP_NOFS);
- if (!data)
- return -ENOMEM;
+ data = kmalloc(dlen, GFP_NOFS | __GFP_NOWARN);
+ if (!data) {
+ /*
+ * Fall-back to the write reserve buffer. Note, we might be
+ * currently on the memory reclaim path, when the kernel is
+ * trying to free some memory by writing out dirty pages. The
+ * write reserve buffer helps us to guarantee that we are
+ * always able to write the data.
+ */
+ allocated = 0;
+ mutex_lock(&c->write_reserve_mutex);
+ data = c->write_reserve_buf;
+ }
data->ch.node_type = UBIFS_DATA_NODE;
key_write(c, key, &data->key);
@@ -736,7 +746,10 @@ int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
goto out_ro;
finish_reservation(c);
- kfree(data);
+ if (!allocated)
+ mutex_unlock(&c->write_reserve_mutex);
+ else
+ kfree(data);
return 0;
out_release:
@@ -745,7 +758,10 @@ out_ro:
ubifs_ro_mode(c, err);
finish_reservation(c);
out_free:
- kfree(data);
+ if (!allocated)
+ mutex_unlock(&c->write_reserve_mutex);
+ else
+ kfree(data);
return err;
}
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