| Message ID | 1367787075-11626-1-git-send-email-khoroshilov@ispras.ru |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Mon, May 06, 2013 at 12:51:15AM +0400, Alexey Khoroshilov wrote: > If memory allocation in ext4_mb_new_group_pa() is failed, > it returns error code, ext4_mb_new_preallocation() propages it, > but ext4_mb_new_blocks() ignores it. > > An observed result was: > - allocation fail means ext4_mb_new_group_pa() does not update ext4_allocation_context; > - ext4_mb_new_blocks() sets ext4_allocation_request->len (ar->len = ac->ac_b_ex.fe_len;) > to number of blocks preallocated (512) instead of number of blocks requested (1); > - that activates update cycle in ext4_splice_branch(): > for (i = 1; i < blks; i++) <-- blks is 512 instead of 1 here > *(where->p + i) = cpu_to_le32(current_block++); > - it iterates 511 times and corrupts a chunk of memory including inode structure; > - page fault happens at EXT4_SB(inode->i_sb) in ext4_mark_inode_dirty(); > - system hangs with 'scheduling while atomic' BUG. > > The patch implements a check for ext4_mb_new_preallocation() error code > and handles its failure as if ext4_mb_regular_allocator() fails. > > Found by Linux File System Verification project (linuxtesting.org). > > Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> > --- > fs/ext4/mballoc.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index b1ed9e0..95c6b0d 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -4401,17 +4401,18 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, > repeat: > /* allocate space in core */ > *errp = ext4_mb_regular_allocator(ac); > + if (!*errp) { > + /* as we've just preallocated more space than > + * user requested orinally, we store allocated "originally" --D > + * space in a special descriptor */ > + if (ac->ac_status == AC_STATUS_FOUND && > + ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) > + *errp = ext4_mb_new_preallocation(ac); > + } > if (*errp) { > ext4_discard_allocated_blocks(ac); > goto errout; > } > - > - /* as we've just preallocated more space than > - * user requested orinally, we store allocated > - * space in a special descriptor */ > - if (ac->ac_status == AC_STATUS_FOUND && > - ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) > - ext4_mb_new_preallocation(ac); > } > if (likely(ac->ac_status == AC_STATUS_FOUND)) { > *errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs); > -- > 1.7.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index b1ed9e0..95c6b0d 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4401,17 +4401,18 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, repeat: /* allocate space in core */ *errp = ext4_mb_regular_allocator(ac); + if (!*errp) { + /* as we've just preallocated more space than + * user requested orinally, we store allocated + * space in a special descriptor */ + if (ac->ac_status == AC_STATUS_FOUND && + ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) + *errp = ext4_mb_new_preallocation(ac); + } if (*errp) { ext4_discard_allocated_blocks(ac); goto errout; } - - /* as we've just preallocated more space than - * user requested orinally, we store allocated - * space in a special descriptor */ - if (ac->ac_status == AC_STATUS_FOUND && - ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len) - ext4_mb_new_preallocation(ac); } if (likely(ac->ac_status == AC_STATUS_FOUND)) { *errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
If memory allocation in ext4_mb_new_group_pa() is failed, it returns error code, ext4_mb_new_preallocation() propages it, but ext4_mb_new_blocks() ignores it. An observed result was: - allocation fail means ext4_mb_new_group_pa() does not update ext4_allocation_context; - ext4_mb_new_blocks() sets ext4_allocation_request->len (ar->len = ac->ac_b_ex.fe_len;) to number of blocks preallocated (512) instead of number of blocks requested (1); - that activates update cycle in ext4_splice_branch(): for (i = 1; i < blks; i++) <-- blks is 512 instead of 1 here *(where->p + i) = cpu_to_le32(current_block++); - it iterates 511 times and corrupts a chunk of memory including inode structure; - page fault happens at EXT4_SB(inode->i_sb) in ext4_mark_inode_dirty(); - system hangs with 'scheduling while atomic' BUG. The patch implements a check for ext4_mb_new_preallocation() error code and handles its failure as if ext4_mb_regular_allocator() fails. Found by Linux File System Verification project (linuxtesting.org). Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> --- fs/ext4/mballoc.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)