Messages in this thread | | | From | "Stephen C. Biggs" <> | Date | Tue, 27 Aug 2002 17:25:17 -0700 | Subject | Bug in kernel code? |
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I posted this to the newsgroup news:linux-kernel but got no response... I'll try here.
While going thru the kernel code for 2.4.17 (uClinux patch) I noticed a problem with functions in 3 files: dcache_init in fs/dcache.c, inode_init in fs/inode.c and in mnt_init in fs/namespace.c
At least on my Redhat 7.3 2.4.18-10 source, in the function
static void __init dcache_init(unsigned long mempages) { struct list_head *d; unsigned long order; unsigned int nr_hash; int i;
/* * A constructor could be added for stable state like the lists, * but it is probably not worth it because of the cache nature * of the dcache. * If fragmentation is too bad then the SLAB_HWCACHE_ALIGN * flag could be removed here, to hint to the allocator that * it should not try to get multiple page regions. */ dentry_cache = kmem_cache_create("dentry_cache", sizeof(struct dentry), 0, SLAB_HWCACHE_ALIGN, NULL, NULL); if (!dentry_cache) panic("Cannot create dentry cache");
#if PAGE_SHIFT < 13 mempages >>= (13 - PAGE_SHIFT); #endif mempages *= sizeof(struct list_head); for (order = 0; ((1UL << order) << PAGE_SHIFT) < mempages; order++) ;
do { u32 tmp;
nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct list_head); d_hash_mask = (nr_hash - 1);
tmp = nr_hash; d_hash_shift = 0; while ((tmp >>= 1UL) != 0UL) d_hash_shift++;
dentry_hashtable = (struct list_head *) __get_free_pages(GFP_ATOMIC, order); } while (dentry_hashtable == NULL && --order >= 0);
........... Notice the --order >=0 in the do while test... since order is declared as an unsigned long, this test is a pointless comparison and never fails, causing an infinite loop if the hashtable is empty.
My fix to this is to change the test to have while (dentry_hashtable == NULL && order-- != 0);
Could someone check me on this?
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