RE: [PATCH 05/19] RMDA/siw: Convert to use vm_account

[Bernard Metzler]

> -----Original Message-----
> From: Alistair Popple <apopple@xxxxxxxxxx>
> Sent: Monday, 6 February 2023 08:48
> To: linux-mm@xxxxxxxxx; cgroups@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; jgg@xxxxxxxxxx; jhubbard@xxxxxxxxxx;
> tjmercier@xxxxxxxxxx; hannes@xxxxxxxxxxx; surenb@xxxxxxxxxx;
> mkoutny@xxxxxxxx; daniel@xxxxxxxx; Daniel Berrange <berrange@xxxxxxxxxx>;
> Alex Williamson <alex.williamson@xxxxxxxxxx>; Alistair Popple
> <apopple@xxxxxxxxxx>; Bernard Metzler <BMT@xxxxxxxxxxxxxx>; Jason Gunthorpe
> <jgg@xxxxxxxx>; Leon Romanovsky <leon@xxxxxxxxxx>; linux-
> rdma@xxxxxxxxxxxxxxx
> Subject: [EXTERNAL] [PATCH 05/19] RMDA/siw: Convert to use vm_account
> 
> Convert to using a vm_account structure to account pinned memory to
> both the mm and the pins cgroup.
> 
> Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx>
> Cc: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
> Cc: Jason Gunthorpe <jgg@xxxxxxxx>
> Cc: Leon Romanovsky <leon@xxxxxxxxxx>
> Cc: linux-rdma@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> ---
>  drivers/infiniband/sw/siw/siw.h       |  3 ++-
>  drivers/infiniband/sw/siw/siw_mem.c   | 21 +++++++--------------
>  drivers/infiniband/sw/siw/siw_verbs.c | 15 ---------------
>  3 files changed, 9 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/siw/siw.h
> b/drivers/infiniband/sw/siw/siw.h
> index 2f3a9cd..6d4aabd 100644
> --- a/drivers/infiniband/sw/siw/siw.h
> +++ b/drivers/infiniband/sw/siw/siw.h
> @@ -13,6 +13,7 @@
>  #include <crypto/hash.h>
>  #include <linux/crc32.h>
>  #include <linux/crc32c.h>
> +#include <linux/vm_account.h>
> 
>  #include <rdma/siw-abi.h>
>  #include "iwarp.h"
> @@ -124,7 +125,7 @@ struct siw_umem {
>  	int num_pages;
>  	bool writable;
>  	u64 fp_addr; /* First page base address */
> -	struct mm_struct *owning_mm;
> +	struct vm_account vm_account;
>  };
> 
>  struct siw_pble {
> diff --git a/drivers/infiniband/sw/siw/siw_mem.c
> b/drivers/infiniband/sw/siw/siw_mem.c
> index f51ab2c..be90121 100644
> --- a/drivers/infiniband/sw/siw/siw_mem.c
> +++ b/drivers/infiniband/sw/siw/siw_mem.c
> @@ -68,7 +68,6 @@ static void siw_free_plist(struct siw_page_chunk *chunk,
> int num_pages,
> 
>  void siw_umem_release(struct siw_umem *umem, bool dirty)
>  {
> -	struct mm_struct *mm_s = umem->owning_mm;
>  	int i, num_pages = umem->num_pages;
> 
>  	for (i = 0; num_pages; i++) {
> @@ -79,9 +78,9 @@ void siw_umem_release(struct siw_umem *umem, bool dirty)
>  		kfree(umem->page_chunk[i].plist);
>  		num_pages -= to_free;
>  	}
> -	atomic64_sub(umem->num_pages, &mm_s->pinned_vm);
> +	vm_unaccount_pinned(&umem->vm_account, umem->num_pages);
> +	vm_account_release(&umem->vm_account);
> 
> -	mmdrop(mm_s);
>  	kfree(umem->page_chunk);
>  	kfree(umem);
>  }
> @@ -365,9 +364,7 @@ struct siw_pbl *siw_pbl_alloc(u32 num_buf)
>  struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
>  {
>  	struct siw_umem *umem;
> -	struct mm_struct *mm_s;
>  	u64 first_page_va;
> -	unsigned long mlock_limit;
>  	unsigned int foll_flags = FOLL_LONGTERM;
>  	int num_pages, num_chunks, i, rv = 0;
> 
> @@ -385,20 +382,16 @@ struct siw_umem *siw_umem_get(u64 start, u64 len,
> bool writable)
>  	if (!umem)
>  		return ERR_PTR(-ENOMEM);
> 
> -	mm_s = current->mm;
> -	umem->owning_mm = mm_s;
>  	umem->writable = writable;
> 
> -	mmgrab(mm_s);
> +	vm_account_init_current(&umem->vm_account);
> 
>  	if (writable)
>  		foll_flags |= FOLL_WRITE;
> 
> -	mmap_read_lock(mm_s);
> +	mmap_read_lock(current->mm);
> 
> -	mlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> -
> -	if (atomic64_add_return(num_pages, &mm_s->pinned_vm) > mlock_limit) {
> +	if (vm_account_pinned(&umem->vm_account, num_pages)) {
>  		rv = -ENOMEM;
>  		goto out_sem_up;
>  	}
> @@ -434,14 +427,14 @@ struct siw_umem *siw_umem_get(u64 start, u64 len,
> bool writable)
>  		}
>  	}
>  out_sem_up:
> -	mmap_read_unlock(mm_s);
> +	mmap_read_unlock(current->mm);
> 
>  	if (rv > 0)
>  		return umem;
> 
>  	/* Adjust accounting for pages not pinned */
>  	if (num_pages)
> -		atomic64_sub(num_pages, &mm_s->pinned_vm);
> +		vm_unaccount_pinned(&umem->vm_account, num_pages);
> 
>  	siw_umem_release(umem, false);
> 
> diff --git a/drivers/infiniband/sw/siw/siw_verbs.c
> b/drivers/infiniband/sw/siw/siw_verbs.c
> index 906fde1..8fab009 100644
> --- a/drivers/infiniband/sw/siw/siw_verbs.c
> +++ b/drivers/infiniband/sw/siw/siw_verbs.c
> @@ -1321,8 +1321,6 @@ struct ib_mr *siw_reg_user_mr(struct ib_pd *pd, u64
> start, u64 len,
>  	struct siw_umem *umem = NULL;
>  	struct siw_ureq_reg_mr ureq;
>  	struct siw_device *sdev = to_siw_dev(pd->device);
> -
> -	unsigned long mem_limit = rlimit(RLIMIT_MEMLOCK);
>  	int rv;
> 
>  	siw_dbg_pd(pd, "start: 0x%pK, va: 0x%pK, len: %llu\n",
> @@ -1338,19 +1336,6 @@ struct ib_mr *siw_reg_user_mr(struct ib_pd *pd, u64
> start, u64 len,
>  		rv = -EINVAL;
>  		goto err_out;
>  	}
> -	if (mem_limit != RLIM_INFINITY) {
> -		unsigned long num_pages =
> -			(PAGE_ALIGN(len + (start & ~PAGE_MASK))) >> PAGE_SHIFT;
> -		mem_limit >>= PAGE_SHIFT;
> -
> -		if (num_pages > mem_limit - current->mm->locked_vm) {
> -			siw_dbg_pd(pd, "pages req %lu, max %lu, lock %lu\n",
> -				   num_pages, mem_limit,
> -				   current->mm->locked_vm);
> -			rv = -ENOMEM;
> -			goto err_out;
> -		}
> -	}

Yes, makes sense. This double checking now and then
in siw_umem_get() was just useless. thanks!

>  	umem = siw_umem_get(start, len, ib_access_writable(rights));
>  	if (IS_ERR(umem)) {
>  		rv = PTR_ERR(umem);
LGTM!
Reviewed-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>

> --
> git-series 0.9.1