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[PATCH] XFS: handle memory allocation failures during log initialisation

To: xfs@xxxxxxxxxxx
Subject: [PATCH] XFS: handle memory allocation failures during log initialisation
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 31 Oct 2008 12:26:06 +1100
When there is no memory left in the system, xfs_buf_get_noaddr()
can fail. If this happens at mount time during xlog_alloc_log()
we fail to catch the error and oops.

Catch the error from xfs_buf_get_noaddr(), and allow other memory
allocations to fail and catch those errors too. Report the error
to the console and fail the mount with ENOMEM.

Tested by manually injecting errors into xfs_buf_get_noaddr() and
xlog_alloc_log().

Version 2:
o remove unnecessary casts of the returned pointer from kmem_zalloc()

Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>
---
 fs/xfs/xfs_log.c |   39 ++++++++++++++++++++++++++++++++++++---
 1 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 5184017..92c20a8 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -563,6 +563,11 @@ xfs_log_mount(
        }
 
        mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
+       if (!mp->m_log) {
+               cmn_err(CE_WARN, "XFS: Log allocation failed: No memory!");
+               error = ENOMEM;
+               goto out;
+       }
 
        /*
         * Initialize the AIL now we have a log.
@@ -601,6 +606,7 @@ xfs_log_mount(
        return 0;
 error:
        xfs_log_unmount_dealloc(mp);
+out:
        return error;
 }      /* xfs_log_mount */
 
@@ -1217,7 +1223,9 @@ xlog_alloc_log(xfs_mount_t        *mp,
        int                     i;
        int                     iclogsize;
 
-       log = (xlog_t *)kmem_zalloc(sizeof(xlog_t), KM_SLEEP);
+       log = kmem_zalloc(sizeof(xlog_t), KM_MAYFAIL);
+       if (!log)
+               return NULL;
 
        log->l_mp          = mp;
        log->l_targ        = log_target;
@@ -1249,6 +1257,8 @@ xlog_alloc_log(xfs_mount_t        *mp,
        xlog_get_iclog_buffer_size(mp, log);
 
        bp = xfs_buf_get_empty(log->l_iclog_size, mp->m_logdev_targp);
+       if (!bp)
+               goto out_free_log;
        XFS_BUF_SET_IODONE_FUNC(bp, xlog_iodone);
        XFS_BUF_SET_BDSTRAT_FUNC(bp, xlog_bdstrat_cb);
        XFS_BUF_SET_FSPRIVATE2(bp, (unsigned long)1);
@@ -1275,13 +1285,17 @@ xlog_alloc_log(xfs_mount_t      *mp,
        iclogsize = log->l_iclog_size;
        ASSERT(log->l_iclog_size >= 4096);
        for (i=0; i < log->l_iclog_bufs; i++) {
-               *iclogp = (xlog_in_core_t *)
-                         kmem_zalloc(sizeof(xlog_in_core_t), KM_SLEEP);
+               *iclogp = kmem_zalloc(sizeof(xlog_in_core_t), KM_MAYFAIL);
+               if (!*iclogp)
+                       goto out_free_iclog;
+
                iclog = *iclogp;
                iclog->ic_prev = prev_iclog;
                prev_iclog = iclog;
 
                bp = xfs_buf_get_noaddr(log->l_iclog_size, mp->m_logdev_targp);
+               if (!bp)
+                       goto out_free_iclog;
                if (!XFS_BUF_CPSEMA(bp))
                        ASSERT(0);
                XFS_BUF_SET_IODONE_FUNC(bp, xlog_iodone);
@@ -1323,6 +1337,25 @@ xlog_alloc_log(xfs_mount_t       *mp,
        log->l_iclog->ic_prev = prev_iclog;     /* re-write 1st prev ptr */
 
        return log;
+
+out_free_iclog:
+       for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
+               prev_iclog = iclog->ic_next;
+               if (iclog->ic_bp) {
+                       sv_destroy(&iclog->ic_force_wait);
+                       sv_destroy(&iclog->ic_write_wait);
+                       xfs_buf_free(iclog->ic_bp);
+                       xlog_trace_iclog_dealloc(iclog);
+               }
+               kmem_free(iclog);
+       }
+       spinlock_destroy(&log->l_icloglock);
+       spinlock_destroy(&log->l_grant_lock);
+       xlog_trace_loggrant_dealloc(log);
+       xfs_buf_free(log->l_xbuf);
+out_free_log:
+       kmem_free(log);
+       return NULL;
 }      /* xlog_alloc_log */
 
 
-- 
1.5.6.5

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