[Devel] [PATCH RHEL8 COMMIT] ms/silence nfscache allocation warnings with kvzalloc

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.26
------>
commit af19368f1d81bb937800aca32a2a02d768537b6e
Author: Rik van Riel <riel at surriel.com>
Date:   Thu May 6 00:59:13 2021 +0300

    ms/silence nfscache allocation warnings with kvzalloc
    
    Currently nfsd_reply_cache_init attempts hash table allocation through
    kmalloc, and manually falls back to vzalloc if that fails. This makes
    the code a little larger than needed, and creates a significant amount
    of serial console spam if you have enough systems.
    
    Switching to kvzalloc gets rid of the allocation warnings, and makes
    the code a little cleaner too as a side effect.
    
    Freeing of nn->drc_hashtbl is already done using kvfree currently.
    
    Signed-off-by: Rik van Riel <riel at surriel.com>
    Signed-off-by: J. Bruce Fields <bfields at redhat.com>
    
    eshatokhin@:
    This patch from mainline kernel (commit 8c38b705b4f4) addresses the same
    issue as the commit fb1f6c63b271 "nfsd: use kvzalloc() to allocate memory
    for drc_hashtbl" in VZ7, prepared by Oleg Babin in the scope of
    https://jira.sw.ru/browse/PSBM-84234. That patch did not make it into
    the mainline kernel for some reason, so I picked the fix from mainline
    instead.
    
    >From the description of commit fb1f6c63b271 in VZ7:
    =============
    The original code uses vzalloc() directly as a fallback path if
    the allocation with kcalloc() failed. But in this case a warning
    about memory allocation failure will be generated even in case
    when the fallback path succeeds. Also kcalloc() can involve retries
    and OOM killer which is undesireable.
    
    kvzalloc() handles all these aspects properly.
    
    [...]
    
    The size of drc_hashtbl depends on totalram_pages and totalhigh_pages
    mm variables and limited to 96k which means 5th memory order.
    
    Use kvzalloc() for drc_hashtbl allocation to fallback to vmalloc()
    in case of high order page is not available at the moment.
    =============
    
    Done in the scope of https://jira.sw.ru/browse/PSBM-127830.
    
    Cherry-picked from ms commit ("8c38b705b4f4 silence nfscache allocation warnings
    with kvzalloc").
    
    Signed-off-by: Evgenii Shatokhin <eshatokhin at virtuozzo.com>
---
 fs/nfsd/nfscache.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index f3595fcead23..3bacc9f82f57 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -173,14 +173,10 @@ int nfsd_reply_cache_init(struct nfsd_net *nn)
 	if (status)
 		goto out_nomem;
 
-	nn->drc_hashtbl = kcalloc(hashsize,
-				sizeof(*nn->drc_hashtbl), GFP_KERNEL);
-	if (!nn->drc_hashtbl) {
-		nn->drc_hashtbl = vzalloc(array_size(hashsize,
-						 sizeof(*nn->drc_hashtbl)));
-		if (!nn->drc_hashtbl)
-			goto out_shrinker;
-	}
+	nn->drc_hashtbl = kvzalloc(array_size(hashsize,
+				sizeof(*nn->drc_hashtbl)), GFP_KERNEL);
+	if (!nn->drc_hashtbl)
+		goto out_shrinker;
 
 	for (i = 0; i < hashsize; i++) {
 		INIT_LIST_HEAD(&nn->drc_hashtbl[i].lru_head);