Messages in this thread | | | From | Suren Baghdasaryan <> | Date | Wed, 3 May 2023 08:18:39 -0700 | Subject | Re: [PATCH 34/40] lib: code tagging context capture support |
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On Wed, May 3, 2023 at 12:36 AM Michal Hocko <mhocko@suse.com> wrote: > > On Mon 01-05-23 09:54:44, Suren Baghdasaryan wrote: > [...] > > +static inline void add_ctx(struct codetag_ctx *ctx, > > + struct codetag_with_ctx *ctc) > > +{ > > + kref_init(&ctx->refcount); > > + spin_lock(&ctc->ctx_lock); > > + ctx->flags = CTC_FLAG_CTX_PTR; > > + ctx->ctc = ctc; > > + list_add_tail(&ctx->node, &ctc->ctx_head); > > + spin_unlock(&ctc->ctx_lock); > > AFAIU every single tracked allocation will get its own codetag_ctx. > There is no aggregation per allocation site or anything else. This looks > like a scalability and a memory overhead red flag to me.
True. The allocations here would not be limited. We could introduce a global limit to the amount of memory that we can use to store contexts and maybe reuse the oldest entry (in LRU fashion) when we hit that limit?
> > > +} > > + > > +static inline void rem_ctx(struct codetag_ctx *ctx, > > + void (*free_ctx)(struct kref *refcount)) > > +{ > > + struct codetag_with_ctx *ctc = ctx->ctc; > > + > > + spin_lock(&ctc->ctx_lock); > > This could deadlock when allocator is called from the IRQ context.
I see. spin_lock_irqsave() then?
Thanks for the feedback! Suren.
> > > + /* ctx might have been removed while we were using it */ > > + if (!list_empty(&ctx->node)) > > + list_del_init(&ctx->node); > > + spin_unlock(&ctc->ctx_lock); > > + kref_put(&ctx->refcount, free_ctx); > -- > Michal Hocko > SUSE Labs
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