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mm/vmalloc: add a safer version of find_vm_area() for debug 

It is unsafe to dump vmalloc area information when trying to do so from
some contexts.  Add a safer trylock version of the same function to do a
best-effort VMA finding and use it from vmalloc_dump_obj().

[applied test robot feedback on unused function fix.]
[applied Uladzislau feedback on locking.]
Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org
Fixes: 98f180837a ("mm: Make mem_dump_obj() handle vmalloc() memory")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reported-by: Zhen Lei <thunder.leizhen@huaweicloud.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Joel Fernandes (Google) 2023-09-04 18:08:04 +00:00 committed by Andrew Morton
parent 7f33105cdd
commit 0818e739b5
1 changed files with 22 additions and 4 deletions
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26
mm/vmalloc.c
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@ -4278,14 +4278,32 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
#ifdef CONFIG_PRINTK #ifdef CONFIG_PRINTK
bool vmalloc_dump_obj(void *object) bool vmalloc_dump_obj(void *object)
{ {
struct vm_struct *vm;
void *objp = (void *)PAGE_ALIGN((unsigned long)object); void *objp = (void *)PAGE_ALIGN((unsigned long)object);
const void *caller;
struct vm_struct *vm;
struct vmap_area *va;
unsigned long addr;
unsigned int nr_pages;
vm = find_vm_area(objp); if (!spin_trylock(&vmap_area_lock))
if (!vm)
return false; return false;
va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
if (!va) {
spin_unlock(&vmap_area_lock);
return false;
}
vm = va->vm;
if (!vm) {
spin_unlock(&vmap_area_lock);
return false;
}
addr = (unsigned long)vm->addr;
caller = vm->caller;
nr_pages = vm->nr_pages;
spin_unlock(&vmap_area_lock);
pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
vm->nr_pages, (unsigned long)vm->addr, vm->caller); nr_pages, addr, caller);
return true; return true;
} }
#endif #endif