Date: Thu, 9 Jan 2020 10:16:48 -0500 From: Mark Johnston <markj@freebsd.org> To: Hans Petter Selasky <hps@selasky.org> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, current@freebsd.org, Jeff Roberson <jeff@freebsd.org>, Konstantin Belousov <kib@freebsd.org> Subject: Re: M_TEMP trouble in 13.0-CURRENT #0 r355131M Message-ID: <20200109151648.GA1953@raichu> In-Reply-To: <100f4e72-ef8b-07dc-b1e1-2a3ef4853d31@selasky.org> References: <4164.1578563950@critter.freebsd.dk> <4e52b23e-32ed-6556-a74e-22c809a17fe0@selasky.org> <f0c4c466-c20f-8824-0138-6b5d45004256@selasky.org> <100f4e72-ef8b-07dc-b1e1-2a3ef4853d31@selasky.org>
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On Thu, Jan 09, 2020 at 12:58:28PM +0100, Hans Petter Selasky wrote:
> Hi Jeff and Konstantin,
>
> You have a logical breakage after the domainset patches for malloc. The size
> used for allocation statistics is not the same like for freeing causing
> messed up "vmstat -m".
Sorry, I committed a different patch in r356555 before seeing this.
> Also you should audit the code for zero-sized allocations, because upon
> alloc, zero-sized is not counted, while on free it is.
Can you explain further? A zero-sized allocation should be rounded up to
16 bytes in all paths.
> See attached patch.
>
> --HPS
> diff --git a/sys/kern/kern_malloc.c b/sys/kern/kern_malloc.c
> index eba9fc3e1ef..aab33873741 100644
> --- a/sys/kern/kern_malloc.c
> +++ b/sys/kern/kern_malloc.c
> @@ -669,8 +669,10 @@ malloc_domain(size_t size, int *indxp, struct malloc_type *mtp, int domain,
> krequests[size >> KMEM_ZSHIFT]++;
> #endif
> va = uma_zalloc_domain(zone, NULL, domain, flags);
> - if (va != NULL)
> + if (__predict_true(va != NULL)) {
> size = zone->uz_size;
> + malloc_type_zone_allocated(mtp, size, indx);
> + }
> *indxp = indx;
>
> return ((void *) va);
> @@ -699,7 +701,8 @@ malloc_domainset(size_t size, struct malloc_type *mtp, struct domainset *ds,
> ret = malloc_domain(size, &indx, mtp, domain, flags);
> } while (ret == NULL &&
> vm_domainset_iter_policy(&di, &domain) == 0);
> - malloc_type_zone_allocated(mtp, ret == NULL ? 0 : size, indx);
> + if (__predict_false(ret == NULL))
> + malloc_type_zone_allocated(mtp, 0, indx);
> } else {
> /* Policy is handled by kmem. */
> ret = malloc_large(&size, ds, flags);
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