Messages in this thread | | | Date | Wed, 8 Mar 2023 09:49:05 +0100 | Subject | Re: [PATCH v2 1/2] maple_tree: Fix mas_skip_node() end slot detection | From | Snild Dolkow <> |
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On 2023-03-07 19:02, Liam R. Howlett wrote: > mas_skip_node() is used to move the maple state to the node with a > higher limit. It does this by walking up the tree and increasing the > slot count. Since slot count may not be able to be increased, it may > need to walk up multiple times to find room to walk right to a higher > limit node. The limit of slots that was being used was the node limit > and not the last location of data in the node. This would cause the > maple state to be shifted outside actual data and enter an error state, > thus returning -EBUSY. > > The result of the incorrect error state means that mas_awalk() would > return an error instead of finding the allocation space. > > The fix is to use mas_data_end() in mas_skip_node() to detect the nodes > data end point and continue walking the tree up until it is safe to move > to a node with a higher limit. > > The walk up the tree also sets the maple state limits so remove the > buggy code from mas_skip_node(). Setting the limits had the unfortunate > side effect of triggering another bug if the parent node was full and > the there was no suitable gap in the second last child, but room in the > next child. > > mas_skip_node() may also be passed a maple state in an error state from > mas_anode_descend() when no allocations are available. Return on such > an error state immediately. > > Reported-by: Snild Dolkow <snild@sony.com> > Link: https://lore.kernel.org/linux-mm/cb8dc31a-fef2-1d09-f133-e9f7b9f9e77a@sony.com/ > Cc: <Stable@vger.kernel.org> > Cc: Peng Zhang <zhangpeng.00@bytedance.com> > Fixes: 54a611b60590 ("Maple Tree: add new data structure") > Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
With the same method as in https://lore.kernel.org/lkml/6f674f9e-9f32-dabb-60be-0e757e145b14@sony.com/, 1000 runs all pass:
linux$ egrep -o 'Failed|Success' qemu.log | sort | uniq -c 1000 Success
If you want it:
Tested-by: Snild Dolkow <snild@sony.com>
//Snild
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