| Message ID | AANLkTim9F8R10hn2hSrAtXt5hsHZmTYNER5gOOy-dC9U@mail.gmail.com |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 2011-03-04 at 17:55 -0500, Matthew L. Creech wrote: > 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. Any feedback is appreciated, thanks! > > Signed-off-by: Matthew L. Creech <mlcreech@gmail.com> > --- > fs/ubifs/journal.c | 24 +++++++++++++++++------- > fs/ubifs/super.c | 1 + > fs/ubifs/ubifs.h | 16 ++++++++++++++++ > 3 files changed, 34 insertions(+), 7 deletions(-) > > diff -purN orig/fs/ubifs/journal.c linux-2.6.37/fs/ubifs/journal.c > --- orig/fs/ubifs/journal.c 2011-03-04 15:44:41.568667187 -0500 > +++ linux-2.6.37/fs/ubifs/journal.c 2011-03-04 17:28:01.878665040 -0500 > @@ -689,8 +689,8 @@ int ubifs_jnl_write_data(struct ubifs_in > const union ubifs_key *key, const void *buf, int len) > { > 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 err, lnum, offs, compr_type, out_len, allocated = 1; > + int dlen = UBIFS_JNL_DATA_NODE_SZ; > struct ubifs_inode *ui = ubifs_inode(inode); > > dbg_jnl("ino %lu, blk %u, len %d, key %s", > @@ -698,9 +698,13 @@ int ubifs_jnl_write_data(struct ubifs_in > 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) { > + /* If kmalloc() fails, fall back to using a shared buffer */ > + allocated = 0; > + mutex_lock(&c->write_reserve_mutex); > + data = &c->write_reserve.node; > + } > > data->ch.node_type = UBIFS_DATA_NODE; > key_write(c, key, &data->key); > @@ -736,7 +740,10 @@ int ubifs_jnl_write_data(struct ubifs_in > 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 +752,10 @@ 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; > } > > diff -purN orig/fs/ubifs/super.c linux-2.6.37/fs/ubifs/super.c > --- orig/fs/ubifs/super.c 2011-03-04 15:44:41.568667187 -0500 > +++ linux-2.6.37/fs/ubifs/super.c 2011-03-04 16:56:35.628665311 -0500 > @@ -1929,6 +1929,7 @@ static int ubifs_fill_super(struct super > 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; > diff -purN orig/fs/ubifs/ubifs.h linux-2.6.37/fs/ubifs/ubifs.h > --- orig/fs/ubifs/ubifs.h 2011-03-04 15:44:41.568667187 -0500 > +++ linux-2.6.37/fs/ubifs/ubifs.h 2011-03-04 17:03:28.408664874 -0500 > @@ -158,6 +158,19 @@ > #define UBIFS_MAX_BULK_READ 32 > > /* > + * How much space is needed for a single write buffer when writing out a > + * journal data node. > + */ > +#define UBIFS_JNL_DATA_NODE_SZ \ > + (UBIFS_DATA_NODE_SZ + UBIFS_BLOCK_SIZE * WORST_COMPR_FACTOR) > + > +/* Used as a static buffer for journal writes, in case kmalloc() fails */ > +union ubifs_write_reserve_buf { > + struct ubifs_data_node node; > + __u8 buf[UBIFS_JNL_DATA_NODE_SZ]; > +}; Hi, I have not looked closely to this, but it generally looks ok, I review better a bit later. However, one quick comment is that this union is not needed. Please, just add a 'void *' buffer straight to 'struct ubifs_info' instead, and allocate it dynamically.
diff -purN orig/fs/ubifs/journal.c linux-2.6.37/fs/ubifs/journal.c --- orig/fs/ubifs/journal.c 2011-03-04 15:44:41.568667187 -0500 +++ linux-2.6.37/fs/ubifs/journal.c 2011-03-04 17:28:01.878665040 -0500 @@ -689,8 +689,8 @@ int ubifs_jnl_write_data(struct ubifs_in const union ubifs_key *key, const void *buf, int len) { 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 err, lnum, offs, compr_type, out_len, allocated = 1; + int dlen = UBIFS_JNL_DATA_NODE_SZ; struct ubifs_inode *ui = ubifs_inode(inode); dbg_jnl("ino %lu, blk %u, len %d, key %s", @@ -698,9 +698,13 @@ int ubifs_jnl_write_data(struct ubifs_in 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) { + /* If kmalloc() fails, fall back to using a shared buffer */ + allocated = 0; + mutex_lock(&c->write_reserve_mutex); + data = &c->write_reserve.node; + } data->ch.node_type = UBIFS_DATA_NODE; key_write(c, key, &data->key); @@ -736,7 +740,10 @@ int ubifs_jnl_write_data(struct ubifs_in 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 +752,10 @@ 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; } diff -purN orig/fs/ubifs/super.c linux-2.6.37/fs/ubifs/super.c --- orig/fs/ubifs/super.c 2011-03-04 15:44:41.568667187 -0500 +++ linux-2.6.37/fs/ubifs/super.c 2011-03-04 16:56:35.628665311 -0500 @@ -1929,6 +1929,7 @@ static int ubifs_fill_super(struct super 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; diff -purN orig/fs/ubifs/ubifs.h linux-2.6.37/fs/ubifs/ubifs.h --- orig/fs/ubifs/ubifs.h 2011-03-04 15:44:41.568667187 -0500 +++ linux-2.6.37/fs/ubifs/ubifs.h 2011-03-04 17:03:28.408664874 -0500 @@ -158,6 +158,19 @@ #define UBIFS_MAX_BULK_READ 32 /* + * How much space is needed for a single write buffer when writing out a + * journal data node. + */ +#define UBIFS_JNL_DATA_NODE_SZ \ + (UBIFS_DATA_NODE_SZ + UBIFS_BLOCK_SIZE * WORST_COMPR_FACTOR) + +/* Used as a static buffer for journal writes, in case kmalloc() fails */ +union ubifs_write_reserve_buf { + struct ubifs_data_node node; + __u8 buf[UBIFS_JNL_DATA_NODE_SZ]; +}; + +/* * Lockdep classes for UBIFS inode @ui_mutex. */ enum { @@ -1249,6 +1262,9 @@ struct ubifs_info { int max_bu_buf_len; struct mutex bu_mutex; struct bu_info bu; + + struct mutex write_reserve_mutex; + union ubifs_write_reserve_buf write_reserve; int log_lebs; long long log_bytes;
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. Any feedback is appreciated, thanks! Signed-off-by: Matthew L. Creech <mlcreech@gmail.com> --- fs/ubifs/journal.c | 24 +++++++++++++++++------- fs/ubifs/super.c | 1 + fs/ubifs/ubifs.h | 16 ++++++++++++++++ 3 files changed, 34 insertions(+), 7 deletions(-)