From d882962f6af2b484b62a7fb05ef959e1bf355fc4 Mon Sep 17 00:00:00 2001 From: "Matthew L. Creech" Date: Fri, 4 Mar 2011 17:55:02 -0500 Subject: 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 Signed-off-by: Artem Bityutskiy --- fs/ubifs/super.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'fs/ubifs/super.c') diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index d4b4cb4..e360c7a 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1213,6 +1213,13 @@ static int mount_ubifs(struct ubifs_info *c) if (c->bulk_read == 1) bu_init(c); + if (!c->ro_mount) { + c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ, + GFP_KERNEL); + if (!c->write_reserve_buf) + goto out_free; + } + c->mounting = 1; err = ubifs_read_superblock(c); @@ -1482,6 +1489,7 @@ out_wbufs: out_cbuf: kfree(c->cbuf); out_free: + kfree(c->write_reserve_buf); kfree(c->bu.buf); vfree(c->ileb_buf); vfree(c->sbuf); @@ -1520,6 +1528,7 @@ static void ubifs_umount(struct ubifs_info *c) kfree(c->cbuf); kfree(c->rcvrd_mst_node); kfree(c->mst_node); + kfree(c->write_reserve_buf); kfree(c->bu.buf); vfree(c->ileb_buf); vfree(c->sbuf); @@ -1605,6 +1614,10 @@ static int ubifs_remount_rw(struct ubifs_info *c) goto out; } + c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ, GFP_KERNEL); + if (!c->write_reserve_buf) + goto out; + err = ubifs_lpt_init(c, 0, 1); if (err) goto out; @@ -1669,6 +1682,8 @@ out: c->bgt = NULL; } free_wbufs(c); + kfree(c->write_reserve_buf); + c->write_reserve_buf = NULL; vfree(c->ileb_buf); c->ileb_buf = NULL; ubifs_lpt_free(c, 1); @@ -1712,6 +1727,8 @@ static void ubifs_remount_ro(struct ubifs_info *c) free_wbufs(c); vfree(c->orph_buf); c->orph_buf = NULL; + kfree(c->write_reserve_buf); + c->write_reserve_buf = NULL; vfree(c->ileb_buf); c->ileb_buf = NULL; ubifs_lpt_free(c, 1); @@ -1942,6 +1959,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent) mutex_init(&c->mst_mutex); mutex_init(&c->umount_mutex); mutex_init(&c->bu_mutex); + mutex_init(&c->write_reserve_mutex); init_waitqueue_head(&c->cmt_wq); c->buds = RB_ROOT; c->old_idx = RB_ROOT; -- cgit v1.1