Messages in this thread | | | Date | Tue, 29 Nov 2011 13:18:07 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v7 3.2-rc2 3/30] uprobes: register/unregister probes. |
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* Peter Zijlstra <peterz@infradead.org> [2011-11-28 16:29:54]:
> On Fri, 2011-11-18 at 16:37 +0530, Srikar Dronamraju wrote: > > +static void __unregister_uprobe(struct inode *inode, loff_t offset, > > + struct uprobe *uprobe) > > +{ > > + struct list_head try_list; > > + struct address_space *mapping; > > + struct vma_info *vi, *tmpvi; > > + struct vm_area_struct *vma; > > + struct mm_struct *mm; > > + loff_t vaddr; > > + > > + mapping = inode->i_mapping; > > + INIT_LIST_HEAD(&try_list); > > + while ((vi = find_next_vma_info(&try_list, offset, > > + mapping, false)) != NULL) { > > + if (IS_ERR(vi)) > > + break; > > So what kind of half-assed state are we left in if we try an unregister > under memory pressure and how do we deal with that? >
Agree, Even I had this concern and wanted to see if there are ways to deal with this.
- One approach would be pass extra GFG flags while we do allocations atleast in the unregister_uprobe.
Drawback of this approach: if the system is already under memory pressure we shouldnt exert more pressure by asking it to repeat.
- The other approach would be to cache these temporary objects while we insert probes. i.e keep these metadata around.
I am sure you wouldnt want to add additional metadata.
- Third approach would be to have a completion/worker routine kick in if unregister_uprobe fails due to memory allocations.
This looks better than the rest.
Do you have any other approaches that we could try?
-- thanks and regards Srikar
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