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    SubjectRe: Possible dcache BUG
    Date
    On Sunday 15 August 2004 04:48, viro@parcelfarce.linux.theplanet.co.uk wrote:
    >On Sun, Aug 15, 2004 at 12:09:44AM -0400, Gene Heskett wrote:
    >> The only thing I've noted in the slabinfo reports is the
    >> ext3_cache was well into 6 digits in kilobytes. Now its only
    >> 15,000 of its normal units (whatever they are) after the reboot.
    >
    >What did dcache numbers look like at that time?

    IIRC the last time I checked before it locked up, dcache was
    in the 57xxx kilobytes area.

    Right now, after about 5 6 hours uptime, that line in raw format
    is:dentry_cache 731159 772632
    and:ext3_inode_cache 1024365 1055817

    Now, this mornings logwatch told me I should go look at the
    logs again, and I found this had occurred several hours earlier:
    -----------
    Aug 14 18:53:24 coyote kernel: Unable to handle kernel paging request at virtual address 0058af03
    Aug 14 18:53:24 coyote kernel: printing eip:
    Aug 14 18:53:24 coyote kernel: c01648bc
    Aug 14 18:53:24 coyote kernel: *pde = 00000000
    Aug 14 18:53:24 coyote kernel: Oops: 0002 [#1]
    Aug 14 18:53:24 coyote kernel: PREEMPT
    Aug 14 18:53:24 coyote kernel: Modules linked in: tuner tvaudio bttv video_buf btcx_risc eeprom snd_seq_oss snd_seq
    _midi_event snd_seq snd_pcm_oss snd_mixer_oss snd_bt87x snd_intel8x0 snd_ac97_codec snd_pcm snd_timer snd_page_allo
    c snd_mpu401_uart snd_rawmidi snd_seq_device snd forcedeth sg
    Aug 14 18:53:24 coyote kernel: CPU: 0
    Aug 14 18:53:24 coyote kernel: EIP: 0060:[<c01648bc>] Not tainted
    Aug 14 18:53:24 coyote kernel: EFLAGS: 00010202 (2.6.8-rc4)
    Aug 14 18:53:24 coyote kernel: EIP is at dispose_list+0x1c/0xa0
    Aug 14 18:53:24 coyote kernel: eax: 0058aeff ebx: ddfc9140 ecx: ddfc9148 edx: c198bef0
    Aug 14 18:53:24 coyote kernel: esi: c198bef0 edi: 00000075 ebp: c198bed8 esp: c198bec0
    Aug 14 18:53:24 coyote kernel: ds: 007b es: 007b ss: 0068
    Aug 14 18:53:24 coyote kernel: Process kswapd0 (pid: 66, threadinfo=c198b000 task=c1978050)
    Aug 14 18:53:24 coyote kernel: Stack: ddfc92e0 c198bec4 c198bec4 c198b000 cb2be2a0 00000080 c198bf04 c0164c37
    Aug 14 18:53:24 coyote kernel: c198bef0 c198b000 00000000 00000080 ddfc9148 cdf9b668 00000080 00000000
    Aug 14 18:53:24 coyote kernel: c198b000 c198bf10 c0164daf 00000080 c198bf44 c0139fd4 00000080 000000d0
    Aug 14 18:53:24 coyote kernel: Call Trace:
    Aug 14 18:53:24 coyote kernel: [<c010476f>] show_stack+0x7f/0xa0
    Aug 14 18:53:25 coyote kernel: [<c0104908>] show_registers+0x158/0x1b0
    Aug 14 18:53:25 coyote kernel: [<c0104a89>] die+0x89/0x100
    Aug 14 18:53:25 coyote kernel: [<c0111725>] do_page_fault+0x1f5/0x553
    Aug 14 18:53:25 coyote kernel: [<c01043d9>] error_code+0x2d/0x38
    Aug 14 18:53:25 coyote kernel: [<c0164c37>] prune_icache+0xb7/0x1f0
    Aug 14 18:53:25 coyote kernel: [<c0164daf>] shrink_icache_memory+0x3f/0x50
    Aug 14 18:53:25 coyote kernel: [<c0139fd4>] shrink_slab+0x134/0x170
    Aug 14 18:53:25 coyote kernel: [<c013b25d>] balance_pgdat+0x1ad/0x1f0
    Aug 14 18:53:25 coyote kernel: [<c013b35f>] kswapd+0xbf/0xd0
    Aug 14 18:53:25 coyote kernel: [<c0102471>] kernel_thread_helper+0x5/0x14
    Aug 14 18:53:25 coyote kernel: Code: 89 50 04 89 02 c7 41 04 00 02 20 00 c7 01 00 01 10 00 8b 83
    -----------------
    which was about 5 hours before the lockup.

    >Anyway, we could try the patch below and see what shows in
    > /proc/fs/ext3 with it [NOTE: patch is completely untested]. It
    > should show major:minor:inumber:mode
    >for all currently allocated ext3 inodes. It won't be 100% accurate
    > (we can miss some entries/get some twice if cache shrinks or grows
    > at the time), but if the leak is so massive, we ought to see a
    > *lot* of duplicates in there. Seeing what kind of inodes really
    > leaks could narrow the things down.
    >
    >See if cat /proc/fs/ext3 | sort | uniq -c | sort -nr gives anything
    > interesting when leak happens (and check it right after boot to see
    > if it works at all and doesn't oops, obviously ;-)
    >
    >diff -urN RC8-current/fs/ext3/super.c RC8-leak/fs/ext3/super.c
    >--- RC8-current/fs/ext3/super.c Sat Aug 14 05:35:37 2004
    >+++ RC8-leak/fs/ext3/super.c Sun Aug 15 04:41:09 2004
    >@@ -35,6 +35,8 @@
    > #include <linux/mount.h>
    > #include <linux/namei.h>
    > #include <linux/quotaops.h>
    >+#include <linux/proc_fs.h>
    >+#include <linux/seq_file.h>
    > #include <asm/uaccess.h>
    > #include "xattr.h"
    > #include "acl.h"
    >@@ -438,6 +440,9 @@
    >
    > static kmem_cache_t *ext3_inode_cachep;
    >
    >+static LIST_HEAD(ext3_list);
    >+static spinlock_t ext3_list_lock = SPIN_LOCK_UNLOCKED;
    >+
    > /*
    > * Called inside transaction, so use GFP_NOFS
    > */
    >@@ -453,11 +458,17 @@
    > ei->i_default_acl = EXT3_ACL_NOT_CACHED;
    > #endif
    > ei->vfs_inode.i_version = 1;
    >+ spin_lock(&ext3_list_lock);
    >+ list_add(&ei->list, &ext3_list);
    >+ spin_unlock(&ext3_list_lock);
    > return &ei->vfs_inode;
    > }
    >
    > static void ext3_destroy_inode(struct inode *inode)
    > {
    >+ spin_lock(&ext3_list_lock);
    >+ list_del_init(&EXT3_I(inode)->list);
    >+ spin_unlock(&ext3_list_lock);
    > kmem_cache_free(ext3_inode_cachep, EXT3_I(inode));
    > }
    >
    >@@ -475,20 +486,82 @@
    > inode_init_once(&ei->vfs_inode);
    > }
    > }
    >+
    >+static void *ext3_cache_start(struct seq_file *m, loff_t *pos)
    >+{
    >+ struct list_head *p;
    >+ loff_t l = *pos;
    >+
    >+ spin_lock(&ext3_list_lock);
    >+ list_for_each(p, &ext3_list)
    >+ if (!l--)
    >+ return list_entry(p, struct ext3_inode_info, list);
    >+ return NULL;
    >+}
    >+
    >+static void *ext3_cache_next(struct seq_file *m, void *v, loff_t
    > *pos) +{
    >+ struct list_head *p = ((struct ext3_inode_info *)v)->list.next;
    >+ (*pos)++;
    >+ return p==&ext3_list ? NULL : list_entry(p, struct
    > ext3_inode_info, list); +}
    >+
    >+static void ext3_cache_stop(struct seq_file *m, void *v)
    >+{
    >+ spin_unlock(&ext3_list_lock);
    >+}
    >+
    >+static int ext3_cache_show(struct seq_file *m, void *v)
    >+{
    >+ struct ext3_inode_info *ei = v;
    >+ struct inode *inode = &ei->vfs_inode;
    >+ seq_printf(m, "%d:%d:%lu:%o",
    >+ MAJOR(inode->i_sb->s_dev),
    >+ MINOR(inode->i_sb->s_dev),
    >+ inode->i_ino,
    >+ inode->i_mode);
    >+ return 0;
    >+}
    >+
    >+static struct seq_operations ext3_cache_op = {
    >+ .start = ext3_cache_start,
    >+ .next = ext3_cache_next,
    >+ .stop = ext3_cache_stop,
    >+ .show = ext3_cache_show
    >+};
    >+
    >+static int ext3_cache_open(struct inode *inode, struct file *file)
    >+{
    >+ return seq_open(file, &ext3_cache_op);
    >+}
    >+
    >+static struct file_operations ext3_cache_operations = {
    >+ .open = ext3_cache_open,
    >+ .read = seq_read,
    >+ .llseek = seq_lseek,
    >+ .release = seq_release,
    >+};
    >
    > static int init_inodecache(void)
    > {
    >+ struct proc_dir_entry *p;
    > ext3_inode_cachep = kmem_cache_create("ext3_inode_cache",
    > sizeof(struct ext3_inode_info),
    > 0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
    > init_once, NULL);
    > if (ext3_inode_cachep == NULL)
    > return -ENOMEM;
    >+ p = create_proc_entry("fs/ext3", S_IRUGO, NULL);
    >+ if (p) {
    >+ p->owner = THIS_MODULE;
    >+ p->proc_fops = &ext3_cache_operations;
    >+ }
    > return 0;
    > }
    >
    > static void destroy_inodecache(void)
    > {
    >+ remove_proc_entry("fs/ext3", NULL);
    > if (kmem_cache_destroy(ext3_inode_cachep))
    > printk(KERN_INFO "ext3_inode_cache: not all structures were
    > freed\n"); }
    >diff -urN RC8-current/include/linux/ext3_fs_i.h
    > RC8-leak/include/linux/ext3_fs_i.h ---
    > RC8-current/include/linux/ext3_fs_i.h Thu Oct 9 17:34:54 2003 +++
    > RC8-leak/include/linux/ext3_fs_i.h Sun Aug 15 04:11:03 2004 @@
    > -107,6 +107,7 @@
    > * by other means, so we have truncate_sem.
    > */
    > struct semaphore truncate_sem;
    >+ struct list_head list;
    > struct inode vfs_inode;
    > };
    ----------
    I'll put this in right now. Thanks.

    --
    Cheers, Gene
    "There are four boxes to be used in defense of liberty:
    soap, ballot, jury, and ammo. Please use in that order."
    -Ed Howdershelt (Author)
    99.24% setiathome rank, not too shabby for a WV hillbilly
    Yahoo.com attorneys please note, additions to this message
    by Gene Heskett are:
    Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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