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SubjectRe: Linux 2.4.5-ac14
Date
Hi Dieter,

On Fri, 15 Jun 2001, Dieter Nützel wrote:
> I see 4.29 GB under shm with your latest try.
> something wrong?

Yes, this is nasty. The appended patch fixes that. (I am not really
happy to need the PG_marker flag for writepage.)

The patch also fixes two other problems:
- shmem_file_setup has to check the given size. Else we can corrupt
kernel memory on 64bit machines. (Thanks to Oliver Paukstadt for
detecting this)
- shmem_remount_fs does not initialize the parameters and thus
corrupts the sizes (detected by Joris van Rantwijk)

Alan, please apply.

Greetings
Christoph

diff -uNr 5-ac14/include/linux/mm.h 5-ac14-fix/include/linux/mm.h
--- 5-ac14/include/linux/mm.h Fri Jun 15 10:37:21 2001
+++ 5-ac14-fix/include/linux/mm.h Fri Jun 15 11:24:06 2001
@@ -357,6 +357,7 @@

#define PageMarker(page) test_bit(PG_marker, &(page)->flags)
#define SetPageMarker(page) set_bit(PG_marker, &(page)->flags)
+#define ClearPageMarker(page) clear_bit(PG_marker, &(page)->flags)

#ifdef CONFIG_HIGHMEM
#define PageHighMem(page) test_bit(PG_highmem, &(page)->flags)
diff -uNr 5-ac14/mm/shmem.c 5-ac14-fix/mm/shmem.c
--- 5-ac14/mm/shmem.c Fri Jun 15 10:09:21 2001
+++ 5-ac14-fix/mm/shmem.c Fri Jun 15 11:37:44 2001
@@ -34,6 +34,7 @@
#define TMPFS_MAGIC 0x01021994

#define ENTRIES_PER_PAGE (PAGE_SIZE/sizeof(unsigned long))
+#define SHMEM_MAX_BLOCKS (SHMEM_NR_DIRECT + ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)

#define SHMEM_SB(sb) (&sb->u.shmem_sb)

@@ -56,10 +57,12 @@
struct inode *inode = (struct inode *)page->mapping->host;
struct shmem_sb_info * sbinfo = SHMEM_SB(inode->i_sb);

- inode->i_blocks -= BLOCKS_PER_PAGE;
- spin_lock (&sbinfo->stat_lock);
- sbinfo->free_blocks++;
- spin_unlock (&sbinfo->stat_lock);
+ if (!PageMarker(page)) {
+ inode->i_blocks -= BLOCKS_PER_PAGE;
+ spin_lock (&sbinfo->stat_lock);
+ sbinfo->free_blocks++;
+ spin_unlock (&sbinfo->stat_lock);
+ }
atomic_dec(&shmem_nrpages);
}

@@ -241,9 +244,10 @@
*entry = swap;
error = 0;
/* Remove the page from the page cache */
- atomic_dec(&shmem_nrpages);
lru_cache_del(page);
+ SetPageMarker(page);
remove_inode_page(page);
+ ClearPageMarker(page);

/* Add it to the swap cache */
add_to_swap_cache(page, swap);
@@ -1062,6 +1066,8 @@
unsigned long max_inodes, inodes;
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);

+ max_blocks = sbinfo->max_blocks;
+ max_inodes = sbinfo->max_inodes;
if (shmem_parse_options (data, NULL, &max_blocks, &max_inodes))
return -EINVAL;

@@ -1110,7 +1116,7 @@
sbinfo->free_blocks = blocks;
sbinfo->max_inodes = inodes;
sbinfo->free_inodes = inodes;
- sb->s_maxbytes = (unsigned long long)(SHMEM_NR_DIRECT + (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)) << PAGE_CACHE_SHIFT;
+ sb->s_maxbytes = (unsigned long long) SHMEM_MAX_BLOCKS << PAGE_CACHE_SHIFT;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = TMPFS_MAGIC;
@@ -1311,9 +1317,11 @@
struct qstr this;
int vm_enough_memory(long pages);

- error = -ENOMEM;
+ if (size > (unsigned long long) SHMEM_MAX_BLOCKS << PAGE_CACHE_SHIFT)
+ return ERR_PTR(-EINVAL);
+
if (!vm_enough_memory((size) >> PAGE_SHIFT))
- goto out;
+ return ERR_PTR(-ENOMEM);

this.name = name;
this.len = strlen(name);
@@ -1321,7 +1329,7 @@
root = tmpfs_fs_type.kern_mnt->mnt_root;
dentry = d_alloc(root, &this);
if (!dentry)
- goto out;
+ return ERR_PTR(-ENOMEM);

error = -ENFILE;
file = get_empty_filp();
@@ -1347,7 +1355,6 @@
put_filp(file);
put_dentry:
dput (dentry);
-out:
return ERR_PTR(error);
}
/*
-
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