Messages in this thread | | | Date | Tue, 28 Nov 2023 12:54:39 -0500 | From | Kent Overstreet <> | Subject | Re: [PATCH 4/7] mm: Centralize & improve oom reporting in show_mem.c |
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On Tue, Nov 28, 2023 at 11:07:18AM +0100, Michal Hocko wrote: > On Wed 22-11-23 18:25:09, Kent Overstreet wrote: > [...] > > 00177 Shrinkers: > > 00177 super_cache_scan: objects: 127 > > 00177 super_cache_scan: objects: 106 > > 00177 jbd2_journal_shrink_scan: objects: 32 > > 00177 ext4_es_scan: objects: 32 > > 00177 bch2_btree_cache_scan: objects: 8 > > 00177 nr nodes: 24 > > 00177 nr dirty: 0 > > 00177 cannibalize lock: 0000000000000000 > > 00177 > > 00177 super_cache_scan: objects: 8 > > 00177 super_cache_scan: objects: 1 > > It would be really great to provide an example on how these numbers are > useful for the oom evaluation.
I should've posted an example from the end of the patch series; I'll do that later today.
> [...] > > @@ -423,4 +426,21 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) > > #ifdef CONFIG_MEMORY_FAILURE > > printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages)); > > #endif > > + > > + buf = kmalloc(4096, GFP_ATOMIC); > > I really do not think we want to allow allocations from the OOM context. > Is there any reason why this cannot be a statically allocated buffer?
You've made this claim before without ever giving any reasoning behind it.
It's GFP_ATOMIC; it has to work from _interrupt_ context, OOM context is fine.
And no, we don't want to burn 4k on a static buffer that is almost never used; people do care about making the kernel run on small systems.
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