Hi,
the `boobytrap' code in __get_free_pages() that was
included in 2.2.15-pre5 has been quite succesful,
the kernel programmers have already managed to fix
a number of bugs found by people running this patch.
However, there are a number of places in the kernel
where the patch to __get_free_pages() is done in an
`indirect' way. This patch adds boobytrap code to
some (most?) of these indirect code paths as well,
allowing us to track down more errors and have a
BugFree(tm) 2.2 kernel sooner.
If you apply this patch your kernel will spit out
a one-line error message on every offence (and a
2-liner on a recursive offence). Each error message
will be of the form:
gfp called by non-running (1) task from c0121e23!
The first word, `gfp' is the function that raises the alarm.
The number between parentheses (1) is the tsk->state.
The last number is the memory address from where we were
called.
You can find this memory address in System.map or in
/proc/ksyms (useful if you have modules). When your
system spits out such a message, you can look up the
offending function in this way:
$ cat /proc/ksyms | sort | grep c0121
c0121474 vfree
c01214dc vmalloc
c01216a4 kmem_cache_create
c0121be0 kmem_cache_shrink
c0122114 kmem_cache_alloc (added for aestetic value)
Of course, you replace the number `c0121' with the
first few numbers of the error message you get...
As we can see, the address from the error message above
(c0121e23) lies between the beginnings of kmem_cache_shrink
and kmem_cache_alloc, that is, it is _in_ kmem_cache_shrink.
When you encounter these error messages, please send them
to linux-kernel, _with_ the names of the functions (because
they differ on every compilation) and, if possible, a short
explanation of what do did to provoke these errors.
kind regards,
Rik
-- The Internet is not a network of computers. It is a network of people. That is its real strength.--- linux-2.2.15pre5/mm/vmscan.c.orig Fri Jan 28 00:13:18 2000 +++ linux-2.2.15pre5/mm/vmscan.c Fri Jan 28 01:46:02 2000 @@ -497,8 +497,11 @@ { if (!do_try_to_free_pages(GFP_KSWAPD)) break; - if (tsk->need_resched) + if (tsk->need_resched) { + if (nr_free_pages > freepages.low) + break; schedule(); + } } run_task_queue(&tq_disk); interruptible_sleep_on_timeout(&kswapd_wait, HZ); --- linux-2.2.15pre5/mm/memory.c.orig Fri Jan 28 00:16:30 2000 +++ linux-2.2.15pre5/mm/memory.c Fri Jan 28 01:45:40 2000 @@ -611,6 +611,12 @@ pte_t pte; unsigned long old_page, new_page; struct page * page_map; + + /* booby trap */ + if (current->state != TASK_RUNNING) { + printk("do_wp_page called by non-running (%d) task from %p!\n", + current->state, __builtin_return_address(0)); + } pte = *page_table; new_page = __get_free_page(GFP_USER); @@ -806,6 +812,13 @@ static int do_anonymous_page(struct task_struct * tsk, struct vm_area_struct * vma, pte_t *page_table, int write_access, unsigned long addr) { pte_t entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot)); + + /* booby trap */ + if (current->state != TASK_RUNNING) { + printk("do_anonymous_page called by non-running (%d) task from %p!\n", + current->state, __builtin_return_address(0)); + } + if (write_access) { unsigned long page = __get_free_page(GFP_USER); if (!page) @@ -932,6 +945,12 @@ pte_t * pte; int ret; + /* booby trap */ + if (current->state != TASK_RUNNING) { + printk("handle_mm_fault called by non-running (%d) task from %p!\n", + current->state, __builtin_return_address(0)); + } + pgd = pgd_offset(vma->vm_mm, address); pmd = pmd_alloc(pgd, address); if (!pmd) --- linux-2.2.15pre5/mm/slab.c.orig Fri Jan 28 00:16:50 2000 +++ linux-2.2.15pre5/mm/slab.c Fri Jan 28 01:40:36 2000 @@ -687,6 +687,12 @@ size_t left_over; size_t align; + /* booby trap */ + if (current->state != TASK_RUNNING) { + printk("kmem_cache_create called by non-running (%d) task from %p!\n", + current->state, __builtin_return_address(0)); + } + /* Sanity checks... */ #if SLAB_MGMT_CHECKS if (!name) { @@ -1589,6 +1595,12 @@ void * kmem_cache_alloc(kmem_cache_t *cachep, int flags) { + /* booby trap */ + if (current->state != TASK_RUNNING) { + printk("kmem_cache_alloc called by non-running (%d) task from %p!\n", + current->state, __builtin_return_address(0)); + } + return __kmem_cache_alloc(cachep, flags); }
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This archive was generated by hypermail 2b29 : Mon Jan 31 2000 - 21:00:20 EST