diff options
| -rw-r--r-- | sys/src/9/port/fault.c | 19 | ||||
| -rw-r--r-- | sys/src/9/port/page.c | 29 |
2 files changed, 29 insertions, 19 deletions
diff --git a/sys/src/9/port/fault.c b/sys/src/9/port/fault.c index 7338181bc..47717ed87 100644 --- a/sys/src/9/port/fault.c +++ b/sys/src/9/port/fault.c @@ -140,15 +140,20 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu) lkp = *pg; lock(lkp); - if(lkp->ref < 1) - panic("fault: lkp->ref %d < 1", lkp->ref); + ref = lkp->ref; + if(ref == 0) + panic("fault %#p ref == 0", lkp); if(lkp->image == &swapimage) - ref = lkp->ref + swapcount(lkp->daddr); - else - ref = lkp->ref; - if(ref == 1 && lkp->image){ - /* save a copy of the original for the image cache */ + ref += swapcount(lkp->daddr); + if(ref == 1 && lkp->image) { + /* + * save a copy of the original for the image cache + * and uncache the page. page might temporarily be + * unlocked while trying to acquire palloc lock so + * recheck ref in case it got grabbed. + */ duppage(lkp); + ref = lkp->ref; } unlock(lkp); diff --git a/sys/src/9/port/page.c b/sys/src/9/port/page.c index 17466ec7a..b004152e9 100644 --- a/sys/src/9/port/page.c +++ b/sys/src/9/port/page.c @@ -335,7 +335,10 @@ retry: * from the freelist, but still in the cache because of * cachepage below. if someone else looks in the cache * before they remove it, the page will have a nonzero ref -* once they finally lock(np). +* once they finally lock(np). This does not happen because +* newpage, auxpage, duppage and lookpage all lock(&palloc) +* so while they hold it nobody is going to grab anything +* from the cache. */ lock(np); if(np->ref != 0) /* should never happen */ @@ -412,23 +415,24 @@ cachepage(Page *p, Image *i) void cachedel(Image *i, ulong daddr) { - Page *f, **l; + Page *f; +retry: lock(&palloc.hashlock); - l = &pghash(daddr); - for(f = *l; f; f = f->hash) { + for(f = pghash(daddr); f; f = f->hash) { if(f->image == i && f->daddr == daddr) { + unlock(&palloc.hashlock); + lock(f); - if(f->image == i && f->daddr == daddr){ - *l = f->hash; - putimage(f->image); - f->image = 0; - f->daddr = 0; + if(f->image != i || f->daddr != daddr) { + unlock(f); + goto retry; } + uncachepage(f); unlock(f); - break; + + return; } - l = &f->hash; } unlock(&palloc.hashlock); } @@ -438,6 +442,7 @@ lookpage(Image *i, ulong daddr) { Page *f; +retry: lock(&palloc.hashlock); for(f = pghash(daddr); f; f = f->hash) { if(f->image == i && f->daddr == daddr) { @@ -448,7 +453,7 @@ lookpage(Image *i, ulong daddr) if(f->image != i || f->daddr != daddr) { unlock(f); unlock(&palloc); - return 0; + goto retry; } if(++f->ref == 1) pageunchain(f); |